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Climate Control System

Refer to Wiring Diagrams Cell 55, Electronic Automatic Temperature Control (EATC) for schematic and connector information.

Vacuum Schematic—Electronic Automatic Temperature Control

SECTION 412-00: Climate Control System - General Information 2000 Town Car Workshop Manual

DIAGNOSIS AND TESTING Procedure revision date: 08/07/2003

Special Tool(s)

Breakout Box, EEC-V Control System 418-049 (014-00950, T94L-50-EEC-V)

Connector, Refrigerant Pressure Line 412-093 (T94P-19623-E)

Fluke 77 III Automotive Meter 105-R0056 or equivalent

Pressure Test Kit 014-R1072 or equivalent

R-134a Manifold Gauge Set 176-R032A or equivalent

Refrigerant Leak Detector 216-00001 or equivalent

Set, A/C Fittings 412-DS028 (014-00333, D93L-19703-B) or equivalent

Vacuum Pump Kit 416-D002 (D95L-7559-A) or equivalent

Worldwide Diagnostic System (WDS) 418-F224, New Generation STAR (NGS) Tester 418-F052, or equivalent scan tool

of 642000 Town Car Workshop Manual

9/19/2011http://www.fordtechservice.dealerconnection.com/pubs/content/~WSYG/~MUS~LEN/20/...

Vacuum connector end view—electronic automatic temperature control

Item Part Number Description

1 18A318 Vacuum control motor, panel/defrost door

2 18A478 Panel/defrost door (full vacuum position)

3 — Defrost airflow

4 — Side window demister airflow

5 18B545 Temperature blend door (full heat position)

6 19860 A/C evaporator core

7 19A813 Air inlet duct door (recirculation position)

8 — Outside air inlet

9 — Recirculated air inlet

10 19805 Blower motor

11 18476 Heater core

12 18A559 Floor/panel door (full vacuum position)

13 — Center console to rear seat airflow

14 — Floor airflow

15 — Vacuum from the engine intake manifold

16 — Vacuum to power brake booster

17 19A563 A/C vacuum check valve

18 19A556 A/C vacuum reservoir tank and bracket

19 — Vacuum to parking brake release

20 19980 Electronic automatic temperature control module

21 18A318 Vacuum control motor, floor/panel door

22 — Panel vent airflow



VACUUM APPLICATIONS CHART—ELECTRONIC AUTOMATIC TEMPERATURE CONTROL

V = vacuum

NV = no vacuum

Inspection and Verification

1. Verify the customer's concern by operating the climate control system to duplicate the condition.

2. Inspect to determine if one of the following mechanical or electrical concerns apply: Visual Inspection Chart

a A leak in the vacuum control circuit can occur during acceleration (slow leak), can exist at all times (large leak) and can exist only when specific functions are selected (indicating a leak in that portion of the circuit). The vacuum hoses used in the passenger compartment control circuit are constructed from PVC plastic material. The vacuum hoses used in the engine compartment are constructed of Hytrel®. Because of the materials used, never pinch the vacuum hoses off during diagnosis to locate a leak. A wood golf tee can be used as a plug when it is necessary to plug one end of the vacuum hose for leak test purposes.

3. If the inspection reveals obvious concern(s) that can be readily identified, repair as required.

4. If the concern remains after the inspection, connect the scan tool to the data link connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the scan tool menu. If the vehicle selection cannot be entered:

� check that the program card is correctly installed.

� check the connections to the vehicle.

� check the ignition switch position.

If the scan tool still does not allow the vehicle selection to be entered, refer to the scan tool manual.

5. Carry out the DATA LINK DIAGNOSTIC TEST using the scan tool. If the scan tool responds with:

� CKT 914 and CKT 915 = ALL MODULE NO RESPONSE/NOT EQUIPPED, go to Communication System Diagnostics in Section 418-00 to diagnose the network concern.

� If the powertrain control module (PCM) is not listed for a communication concern, turn the A/C controls to OFF and execute the self-test diagnostics for the PCM.

� If the EATC module is not listed for a communication concern, execute the self-test diagnostics for the EATC module.

6. If any PCM or EATC DTCs are retrieved, and are related to the concern, go to the Powertrain Control Module Diagnostic Trouble Code (DTC) Index or the Electronic Automatic Temperature Control (EATC) Module Diagnostic Trouble Code (DTC) Index to continue the diagnostics.

7. If no DTCs related to the concern are retrieved, go to the Symptom Chart to continue the diagnostics.

8. If the electronic automatic temperature control module cannot be accessed by the scan tool, go to Pinpoint Test H.

Electronic Automatic Temperature Control Module Self-Test

Port Number Circuit Circuit Function

1 — Not used

2 Blue Panel/defrost door

3 Yellow Floor/panel door

4 Black Source vacuum

5 — Not used

6 Red Floor/panel door

Vacuum Harness Hose Color Function

Manual Override Selector Buttons

OFF MAX A/C VENT PNL & FLR FLOOR FLR & DEF DEFROST

Red Full floor NV NV NV NV V NV NV

Yellow Floor/panel (partial) NV NV NV V V V NV

Blue Panel/defrost NV V V V NV NV NV

Black Source V V V V V V V

Mechanical Electrical

� Loose, missing or damaged A/C compressor drive belt � Loose or disconnected A/C clutch � Loose, misrouted or damaged vacuum lines

� Broken or leaking vacuum control motora

� Broken or leaking refrigerant lines � Obstructed in-car temperature sensor � Disconnected in-car temperature aspirator hose

a

� Open fuses � Blower motor inoperative � A/C compressor inoperative � Circuitry open/shorted � Disconnected electrical connectors � Cooling fan inoperative



� The EATC module self-test will not detect concerns associated with data link messages like engine coolant temperature or vehicle speed signals. A scan tool must be used to retrieve these concerns.

� The EATC module self-test will detect concerns in the system control functions and will display hard diagnostic trouble codes (DTCs). Hard DTCs identify faults which are present during the self- test. The vehicle interior temperature should be between 4-32°C (40-90°F) when carrying out the self-test. If the temperatures are not within the specified ranges, false in-car temperature sensor DTCs will be displayed.

� The self-test can be initiated at any time. Normal operation of the system stops when the self-test is activated.

� To enter the self-test, press the OFF and FLOOR buttons simultaneously and then press the AUTOMATIC button within two seconds. The display will show a pulse tracer going around the center of the display window. The test may run as long as 30 seconds. Record all DTCs displayed.

� If any DTCs appear during the self-test, follow the diagnostics procedure given under ACTION for each DTC given.

� If a condition exists but no DTCs appear during the self-test, refer to the Symptom Chart Condition: The EATC System Is Inoperative, Intermittent or Incorrect Operation.

� To exit the self-test and clear all DTCs, press the FRONT DEFROST button. The vacuum fluorescent display window will show 888 and all function symbols for one second. The EATC control assembly will then turn OFF (display blank) and all DTCs will be cleared.

� Always exit the self-test before powering the system down (system turned OFF).

Electronic Automatic Temperature Control Module — Display Continuous Codes

� This function will display continuous (intermittent) codes and hard faults that occur during normal operation.

� The display of continuous codes can be initiated at any time. Normal operation of the system stops when the display of continuous codes is activated. Note that "°C" will be displayed while in this mode.

� To display continuous codes, press the OFF and PANEL buttons simultaneously and then release and within two seconds press the AUTO button.

� To exit the display of continuous codes, press the FRONT DEFROST button. This will exit and clear all DTCs. Press the FLOOR button to exit without clearing DTCs set before the last ignition cycle.

� Always exit continuous codes display before powering the system down (system turned off).

� Continuous DTCs are saved only after an ignition cycle.

� Continuous DTCs will be deleted after 80 ignition switch ON cycles after the intermittent condition occurs.

Powertrain Control Module (PCM) Diagnostic Trouble Code (DTC) Index

ELECTRONIC AUTOMATIC TEMPERATURE CONTROL (EATC) MODULE DIAGNOSTIC TROUBLE CODE (DTC) INDEX

Symptom Chart

DTC Description Action

P1460 WOT A/C cutout internal driver malfunction REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.

P1469 Low A/C cycling period REFER to thePowertrain Control/Emissions Diagnosis (PC/ED) manual.

P1474 Low speed fan internal driver failure REFER to thePowertrain Control/Emissions Diagnosis (PC/ED) manual.

P1479 High speed fan internal driver failure REFER to thePowertrain Control/Emissions Diagnosis (PC/ED) manual.

P1464 A/C demand out of self-test range REFER to thePowertrain Control/Emissions Diagnosis (PC/ED) manual.

DTCEATC (Intermittent) Run-Time Faults or (Hard) Self-

Test Faults Description Action to take

B1249 249 Blend door short —

— — Blend door failure GO to Pinpoint Test A.

B1251 1251 A/C in-car temperature sensor open circuit GO to Pinpoint Test B.

B1253 1253 A/C in-car temperature sensor short to ground GO to Pinpoint Test B.

B1255 1255 A/C ambient temperature sensor open circuit GO to Pinpoint Test C.

B1257 1257 A/C ambient temperature sensor short to ground GO to Pinpoint Test C.

B1261 1261 A/C solar radiation sensor circuit short to ground GO to Pinpoint Test D.

B2416 2416 Recirc door short recirc door failure GO to Pinpoint Test E.

U1041 N/A SCP invalid or missing data for function read vehicle speed

REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.

U1073 N/A SCP invalid or missing data for engine coolant REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.

U1222 N/A SCP invalid or missing data for interior lamps GO to Section 417-02, Inspection and Verification to continue diagnosis.

U1235 N/A SCP invalid or missing data for displays GO to Section 413-08, Inspection and Verification to continue diagnosis.

SYMPTOM CHART

Condition Possible Sources Action

� No communication with the electronic automatic temperature control module

� Circuitry short or open. � EATC module communication network.

� GO to Pinpoint Test F.

� The EATC system is inoperative, intermittent or incorrect operation � Circuitry short or open. � Input sensor(s) or erratic input signals. � Charging system. � Automatic temperature control sensor hose and

elbow.

� GO to Pinpoint Test G.

� Incorrect/erratic direction of airflow from outlet � No vacuum to the A/C control. � A/C control leaks vacuum. � Airflow door binding or stuck. � Vacuum hose, kinked or pinched. � Vacuum control motor. � A/C vacuum check valve. � A/C vacuum reservoir tank and bracket. � Vacuum actuator arm not connected to the door

crank.

� GO to Pinpoint Test H.

� Insufficient, erratic, or no heat � Low engine coolant level. � Engine overheating. � Plugged or partially plugged heater core.

� GO to Pinpoint Test I.



Pinpoint Tests

PINPOINT TEST A: DTC B1249 — BLEND DOOR FAILURE

� Temperature blend door binding or stuck. � A/C electric blend door actuator. � Blend door circuit open/shorted.

� The air conditioning (A/C) is inoperative/does not operate correctly � Open fuse. � A/C clutch relay. � Circuitry short or open. � A/C cycling switch. � A/C system discharged or low charge. � A/C pressure cutoff switch. � A/C control.

� GO to Pinpoint Test J.

� The air conditioning (A/C) is always on � Circuitry short or open. � A/C control. � A/C clutch relay.

� GO to Pinpoint Test K.

� The steering wheel control switch is inoperative/does not operate correctly

� Circuitry short or open. � Steering wheel control switch. � Clockspring. � Steering wheel wiring harness. � Speed control module. � EATC module.

� GO to Pinpoint Test L.

� The blower motor is inoperative � Circuitry short or open. � Blower motor. � Blower motor speed control. � Blower motor relay.

� GO to Pinpoint Test M.

� The blower motor does not operate correctly � Blower motor speed control. � EATC module. � Circuitry short or open.

� GO to Pinpoint Test N.

� The temperature set point does not repeat after turning the ignition switch off

� Open fuse. � Circuitry short or open. � EATC module.

� GO to Pinpoint Test O.

� The temperature display will not switch between Celsius and Fahrenheit � Circuitry short or open. � EATC module.

� GO to Pinpoint Test P.

� The rear audio/climate control switch is inoperative/does not operate correctly

� Circuitry short or open. � Rear audio/climate control switch. � Rear audio/climate control module. � Audio control module (ACM). � EATC module.

� GO to Pinpoint Test Q.

CONDITIONS DETAILS/RESULTS/ACTIONS

A1 CHECK THE ACTUATOR CLOCKWISE OPERATION (FULL COOL)

EATC Module C227 and C281

Connect a fused jumper lead between the EATC module C227 pin 26, circuit 246 (VT) and the EATC module C281 pin 2, circuit 729 (RD/WH). Connect a second fused jumper lead between the EATC module C227 pin 13, circuit 245 (BN/LG) and the EATC module C281 pin 3, circuit 57 (BK).

� Does the temperature blend door actuator motor drive clockwise?

Yes GO to A2.

No GO to A3.

A2 CHECK THE ACTUATOR COUNTERCLOCKWISE OPERATION (FULL HOT)

Connect a fused jumper lead between the EATC module C227 pin 13, circuit 245 (BN/LG) and the EATC module C281 pin 2, circuit 729 (RD/WH). Connect a second fused jumper lead between the EATC module C227 pin 26, circuit 246 (VT) and the EATC module C281 pin 3, circuit 57 (BK).



� Does the temperature blend door actuator motor drive counterclockwise?

Yes GO to A10.

No GO to A3.

A3 CHECK CIRCUIT 246 (VT) FOR A SHORT

Temperature Blend Door Actuator C282

Measure the resistance between the EATC module C227 pin 26, circuit 246 (VT) and ground.

� Is the resistance greater than 10,000 ohms?

Yes GO to A4.

No REPAIR circuit 246 (VT). CLEAR the DTCs. REPEAT the self-test.

A4 CHECK CIRCUIT 245 (BN/LG) FOR A SHORT TO GROUND

Measure the resistance between the EATC module C227 pin 13, circuit 245 (BN/LG) and ground.


Yes GO to A5.

No REPAIR circuit 245 (BN/LG). CLEAR the DTCs. REPEAT the self-test.

A5 CHECK CIRCUIT 246 (VT) FOR AN OPEN

Measure the resistance between the EATC module C227 pin 26, circuit 246 (VT) and the temperature blend door actuator C282 pin 6, circuit 246 (VT).



� Is the resistance less than 5 ohms?

Yes GO to A6.

No REPAIR circuit 246 (VT). CLEAR the DTCs. REPEAT the self-test.

A6 CHECK CIRCUIT 245 (BN/LG) FOR AN OPEN

Measure the resistance between the EATC module C227 pin 13, circuit 245 (BN/LG) and the temperature blend door actuator C282 pin 1, circuit 245 (BN/LG).


Yes GO to A7.

No REPAIR circuit 245 (BN/LG). CLEAR the DTCs. REPEAT the self-test.

A7 CHECK CIRCUIT 246 (VT) AND CIRCUIT 245 (BN/LG) FOR A SHORT TO POWER

Measure the voltage between EATC module C227 pin 26, circuit 246 (VT) and ground. Measure the voltage between EATC module C227 pin 13, circuit 245 (BN/LG) and ground.

� Is voltage present?

Yes REPAIR the affected circuit for a short to power. TEST the system for normal operation.

No GO to A8.

A8 CHECK CIRCUIT 245 (BN/LG) AND 246 (VT) FOR A SHORT TOGETHER

Measure the resistance between EATC module C227 pin 13, circuit 245 (BN/LG) and EATC module C227 pin 26, circuit 246 (VT).


Yes REPAIR circuit 245 (BN/LG) and circuit 246 (VT) for a short together. TEST the system for normal operation.

No GO to A9.

A9 CHECK THE ACTUATOR OPERATION

Remove the temperature blend door actuator. Refer to Section 412-04.




With the actuator driveshaft disengaged from the temperature blend door, drive the temperature blend door actuator full COOL. Refer to Step A1.

With the actuator driveshaft disengaged from the temperature blend door, drive the temperature blend door actuator full HOT. Refer to Step A2.

� Does the temperature blend door actuator drive both clockwise and counterclockwise?

Yes REPAIR the temperature blend door for a blocked or binding condition. CLEAR the DTCs. REPEAT the self-test.

No INSTALL a new temperature blend door actuator. CLEAR the DTCs. REPEAT the self-test.

A10 CHECK THE FEEDBACK POTENTIOMETER TOTAL RESISTANCE

Recirculation Door Actuator C208

Drive the temperature blend door actuator full COOL. Refer to Step A1.

Measure the resistance between the EATC module C281 pin 6, circuit 436 (RD/LG) and the EATC module C227 pin 9, circuit 438 (RD/WH).

� Is the resistance between 5,000 and 7,000 ohms?

Yes GO to A14.

No If the resistance is greater than 7,000 ohms, GO to A11 . If the resistance is less than 5,000 ohms, GO to A13 .

A11 CHECK CIRCUIT 436 (RD/LG) FOR AN OPEN


Measure the resistance between the EATC module C281 pin 6, circuit 436 (RD/LG) and the temperature blend door actuator C282 pin 5, circuit 436 (RD/LG).




Yes GO to A12.

No REPAIR circuit 436 (RD/LG). CLEAR the DTCs. REPEAT the self-test.

A12 CHECK CIRCUIT 438 (RD/WH) FOR AN OPEN

Measure the resistance between the EATC module C227 pin 9, circuit 438 (RD/WH) and the temperature blend door actuator C282 pin 4, circuit 438 (RD/WH).


Yes INSTALL a new temperature blend door actuator. TEST the system for normal operation.

No REPAIR circuit 438 (RD/WH). CLEAR the DTCs. REPEAT the self-test.

A13 CHECK CIRCUIT 438 (RD/WH) FOR A SHORT TO CIRCUIT 436 (RD/LG)


Measure the resistance between EATC module C227 pin 9, circuit 438 (RD/WH) and EATC module C281 pin 6, circuit 436 (RD/LG).



No REPAIR circuit 438 (RD/WH) for a short to circuit 436 (RD/LG). TEST the system for normal operation.

A14 CHECK THE FEEDBACK POTENTIOMETER LOW SIDE RESISTANCE




Measure the resistance between the EATC module C281 pin 18, circuit 437 (YE/LG) and the EATC module C227 pin 9, circuit 438 (RD/WH).

� Is the resistance between 250 and 1,500 ohms?

Yes GO to A17.

No If the resistance is greater than 1,500 ohms, GO to A15 . If the resistance is less than 250 ohms, GO to A16 .

A15 CHECK CIRCUIT 437 (YE/LG) FOR AN OPEN


Measure the resistance between the EATC module C281 pin 18, circuit 437 (YE/LG) and the temperature blend door actuator C282 pin 3, circuit 437 (YE/LG).



No REPAIR circuit 437 (YE/LG). CLEAR the DTCs. REPEAT the self-test.

A16 CHECK CIRCUIT 438 (RD/WH) AND CIRCUIT 437 (YE/LG) FOR A SHORT TOGETHER


Measure the resistance between EATC module C281 pin 9, circuit 438 (RD/WH) and EATC module C227 pin 18, circuit 437 (YE/LG).



No REPAIR circuit 438 (RD/WH) and circuit 437 (YE/LG) for a short together. TEST the system for normal operation.

A17 CHECK THE FEEDBACK POTENTIOMETER HIGH SIDE RESISTANCE




Measure the resistance between the EATC module C281 pin 6, circuit 436 (RD/LG) and the EATC module C281 pin 18, circuit 437 (YE/LG).


Yes GO to A19.

No If the resistance is greater than 6,000 ohms, INSTALL a new temperature blend door actuator. CLEAR the DTCs. REPEAT the self-test. If the resistance is less than 3,500 ohms, GO to A18 .

A18 CHECK CIRCUIT 437 (YE/LG) FOR A SHORT TO CIRCUIT 436 (RD/LG)

Measure the resistance between EATC module C281 pin 6, circuit 436 (RD/LG) and EATC module C281 pin 18, circuit 437 (YE/LG).



No REPAIR circuit 437 (YE/LG) for a short to circuit 436 (RD/LG). TEST the system for normal operation.

A19 CHECK CIRCUIT 436 (RD/LG) AND CIRCUIT 437 (YE/LG) FOR A SHORT TO GROUND


Measure the resistance between EATC module C281 pin 6, circuit 436 (RD/LG) and ground. Measure the resistance between EATC module C281 pin 18, circuit 437 (YE/LG) and ground.

� Are the resistances greater than 10,000 ohms?

Yes GO to A20.

No REPAIR the affected circuit for a short to ground. TEST the system for normal operation.

A20 CHECK CIRCUITS 436 (RD/LG), 437 (YE/LG) AND 438 (RD/WH) FOR A SHORT TO POWER



PINPOINT TEST B: DTC B1251 OR DTC B1253 — A/C IN-CAR TEMPERATURE SENSOR OPEN CIRCUIT OR SHORT TO GROUND

Measure the voltage between EATC module C281 pin 6, circuit 436 (RD/LG), EATC module C281 pin 18, circuit 437 (YE/LG) and EATC module C227 pin 9, circuit 438 (RD/WH) and ground.


Yes REPAIR the affected circuit for a short to power. TEST the system for normal operation.

No INSPECT for a broken door or linkage. If no condition is found, INSTALL a new EATC module. TEST the system for normal operation.


B1 CHECK THE SENSOR RESISTANCE

In-Car Temperature Sensor C293

Measure the resistance between the in-car temperature sensor pins, component side.

Note the ambient temperature and compare the in-car temperature sensor resistance with the table below.

Temperature Resistance

10-20°C (50-68°F) 37,000-58,000 ohms

20-30°C (68-86°F) 24,000-37,000 ohms

30-40°C (86-104°F) 16,000-24,000 ohms

� Is the resistance within the specified values for the temperature range?

Yes GO to B2.

No INSTALL a new in-car temperature sensor. CLEAR the DTCs. REPEAT the self-test.

B2 CHECK THE EATC MODULE OUTPUT VOLTAGE

Press the AUTO button on the EATC module.

Measure the voltage between the in-car temperature sensor C293, circuit 790 (WH/OG) and circuit 470 (PK/BK).



� Is the voltage between 4.7 and 5.1 volts?

Yes INSTALL a new EATC module. TEST the system for normal operation.

No If diagnosing DTC B1251, GO to B3 . If diagnosing DTC B1253, GO to B5 .

B3 CHECK CIRCUIT 790 (WH/OG) FOR AN OPEN

EATC Module C227

Measure the resistance between the EATC module C227 pin 21, circuit 790 (WH/OG) and the in-car temperature sensor C293, circuit 790 (WH/OG).


Yes GO to B4.

No REPAIR circuit 790 (WH/OG). CLEAR the DTCs. REPEAT the self-test.

B4 CHECK CIRCUIT 470 (PK/BK) FOR AN OPEN

EATC Module C281

Measure the resistance between the EATC module C281 pin 4, circuit 470 (PK/BK) and the in-car temperature sensor C293, circuit 470 (PK/BK).


Yes INSTALL a new EATC module. CLEAR the DTCs. REPEAT the self-test.

No REPAIR circuit 470 (PK/BK). CLEAR the DTCs. REPEAT the self-test.

B5 CHECK CIRCUIT 790 (WH/OG) FOR A SHORT TO CIRCUIT 470 (PK/BK)



PINPOINT TEST C: DTC B1255 OR DTC B1257— A/C AMBIENT TEMPERATURE SENSOR OPEN CIRCUIT OR SHORT TO GROUND

EATC Module C281

Measure the resistance between the in-car temperature sensor C293, circuit 790 (WH/OG) and circuit 470 (PK/BK).


Yes GO to B6.

No REPAIR circuit 790 (WH/OG) for a short to circuit 470 (PK/BK). TEST the system for normal operation.

B6 CHECK CIRCUIT 790 (WH/OG) FOR A SHORT TO GROUND

EATC Module C281

Measure the resistance between the EATC module C227 pin 21, circuit 790 (WH/OG) and ground.



No REPAIR circuit 790 (WH/OG) for a short to ground. TEST the system for normal operation.


C1 CHECK THE AMBIENT TEMPERATURE SENSOR RESISTANCE

Ambient Temperature Sensor C160

Measure the resistance between the ambient temperature sensor pins, component side.



Note the ambient temperature and compare the ambient temperature sensor resistance with the table below.

Temperature Resistance

10-20°C (50-68°F) 37,000-58,000 ohms

20-30°C (68-86°F) 24,000-37,000 ohms

30-40°C (86-104°F) 16,000-24,000 ohms

� Is the resistance within the specified values for the temperature range?

Yes GO to C2.

No INSTALL a new ambient air temperature sensor and bracket (19E702). CLEAR the DTCs. REPEAT the self-test.

C2 CHECK THE EATC MODULE OUTPUT VOLTAGE


Measure the voltage between the ambient temperature sensor C160, circuit 767 (LB/OG) and circuit 470 (PK/BK).



No If diagnosing DTC B1255, GO to C3 . If diagnosing DTC 1257, GO to C5 .

C3 CHECK CIRCUIT 767 (LB/OG) FOR AN OPEN

EATC Module C281

Measure the resistance between the EATC module C281 pin 7, circuit 767 (LB/OG) and the ambient temperature sensor C160, circuit 767 (LB/OG).


Yes GO to C4.



PINPOINT TEST D: DTC B1261 — A/C SOLAR RADIATION SENSOR CIRCUIT SHORT TO GROUND

No REPAIR circuit 767 (LB/OG). CLEAR the DTCs. REPEAT the self-test.

C4 CHECK CIRCUIT 470 (PK/BK) FOR AN OPEN

Measure the resistance between the EATC module C281 pin 4, circuit 470 (PK/BK) and the ambient temperature sensor C160, circuit 470 (PK/BK).


Yes INSTALL a new EATC module. REPEAT the self-test.

No REPAIR circuit 470 (PK/BK). CLEAR the DTCs. REPEAT the self-test.

C5 CHECK CIRCUIT 767 (LB/OG) FOR A SHORT TO CIRCUIT 470 (PK/BK)


Measure the resistance between the in-car temperature sensor C160, circuit 767 (LB/OG) and circuit 470 (PK/BK).


Yes GO to C6.

No REPAIR circuit 767 (LB/OG) for a short to ground. TEST the system for normal operation.

C6 CHECK CIRCUIT 767 (LB/OG) FOR A SHORT TO GROUND

Measure the resistance between the EATC module C281 pin 7, circuit 767 (LB/OG) and ground.



No REPAIR circuit 767 (LB/OG) for a short to ground. TEST the system for normal operation.




D1 CHECK THE SOLAR RADIATION SENSOR RESISTANCE

Solar Radiation Sensor C231

NOTE: Connect the ground lead of the multimeter to the sensor ground circuit 470 (PK/BK).

Measure the resistance between the solar radiation sensor pins, component side.

� Is the resistance greater than 0 ohms?

Yes GO to D2.

No INSTALL a new solar radiation sensor. CLEAR the DTCs. REPEAT the self-test.

D2 CHECK THE EATC MODULE OUTPUT VOLTAGE


Measure the voltage between the solar radiation sensor C231, circuit 468 (BN) and circuit 470 (PK/BK).



No GO to D3.

D3 CHECK CIRCUIT 468 (BN) FOR A SHORT TO GROUND

EATC Module C281

Measure the resistance between the EATC module C281 pin 20, circuit 468 (BN) and ground.



PINPOINT TEST E: DTC B2416 — RECIRCULATION DOOR FAILURE


Yes GO to D4.

No REPAIR circuit 468 (BN). CLEAR the DTCs. REPEAT the self-test.

D4 CHECK CIRCUIT 468 (BN) FOR A SHORT TO CIRCUIT 470 (PK/BK)


Measure the resistance between the solar radiation sensor C231, circuit 468 (BN) and circuit 470 (PK/BK).



No REPAIR circuit 468 (BN) for a short to circuit 470 (PK/BK).


E1 CHECK THE ACTUATOR CLOCKWISE OPERATION


Connect a fused jumper lead between the EATC module C227 pin 25, circuit 660 (YE/LG) and the EATC module C281 pin 2, circuit 729 (RD/WH). Connect a second fused jumper lead between the EATC module C227 pin 12, circuit 1069 (OG/LB) and the EATC module C281 pin 3, circuit 57 (BK).

� Does the recirculation door actuator motor drive clockwise?

Yes GO to E2.

No GO to E3.

E2 CHECK THE ACTUATOR COUNTERCLOCKWISE OPERATION

Connect a fused jumper lead between the EATC module C227 pin 12, circuit 1069 (OG/LB) and the EATC module C281 pin 2, circuit 729 (RD/WH). Connect a second fused jumper lead between the EATC module C227 pin 25, circuit 660 (YE/LG) and the EATC module C281 pin 3, circuit 57 (BK).



� Does the recirculation door actuator motor drive counterclockwise?

Yes GO to E8.

No GO to E3.

E3 CHECK CIRCUIT 660 (YE/LG) FOR A SHORT TO GROUND


Measure the resistance between the EATC module C227 pin 25, circuit 660 (YE/LG) and ground.


Yes GO to E4.


E4 CHECK CIRCUIT 1069 (OG/LB) FOR A SHORT TO GROUND

Measure the resistance between the EATC module C227 pin 12, circuit 1069 (OG/LB) and ground.


Yes GO to E5.

No REPAIR circuit 1069 (OG/LB). CLEAR the DTCs. REPEAT the self-test.

E5 CHECK CIRCUIT 660 (YE/LG) FOR AN OPEN

Measure the resistance between the EATC module C227 pin 25, circuit 660 (YE/LG) and the recirculation door actuator C208 pin 6, circuit 660 (YE/LG).




Yes GO to E6.


E6 CHECK CIRCUIT 1069 (OG/LB) FOR AN OPEN

Measure the resistance between the EATC module C227 pin 12, circuit 1069 (OG/LB) and the recirculation door actuator C208 pin 1, circuit 1069 (OG/LB).


Yes GO to E7.

No REPAIR circuit 1069 (OG/LB). CLEAR the DTCs. REPEAT the self-test.

E7 CHECK THE ACTUATOR OPERATION

Remove the recirculation door actuator. Refer to Section 412-04.


With the actuator driveshaft disengaged from the recirculation door, drive the recirculation door actuator clockwise. Refer to Step E1.

With the actuator driveshaft disengaged from the recirculation door, drive the recirculation door actuator counterclockwise. Refer to Step E2.

� Does the recirculation door actuator drive both clockwise and counterclockwise?

Yes REPAIR the recirculation door for a blocked or binding condition. CLEAR the DTCs. REPEAT the self-test.

No INSTALL a new recirculation door actuator. CLEAR the DTCs. REPEAT the self-test.

E8 CHECK THE FEEDBACK POTENTIOMETER TOTAL RESISTANCE


Drive the recirculation door actuator full counterclockwise. Refer to Step E2.



Measure the resistance between the EATC module C281 pin 6, circuit 436 (RD/LG) and the EATC module C227 pin 9, circuit 438 (RD/WH).


Yes GO to E13.

No GO to E9.

E9 CHECK CIRCUIT 436 (RD/LG) FOR AN OPEN


Measure the resistance between the EATC module C281 pin 6, circuit 436 (RD/LG) and the recirculation door actuator C208 pin 5, circuit 436 (RD/LG).


Yes GO to E10.


E10 CHECK CIRCUIT 438 (RD/WH) FOR AN OPEN

Measure the resistance between the EATC module C227 pin 9, circuit 438 (RD/WH) and the recirculation door actuator C208 pin 4, circuit 438 (RD/WH).


Yes GO to E11.


E11 CHECK CIRCUIT 436 (RD/LG)



Measure the resistance between the EATC module C281 pin 6, circuit 436 (RD/LG) and ground.


Yes GO to E12.


E12 CHECK CIRCUIT 438 (RD/WH)

Measure the resistance between the EATC module C227 pin 9, circuit 438 (RD/WH) and ground.


Yes INSTALL a new recirculation door actuator. CLEAR the DTCs. REPEAT the self-test.


E13 CHECK THE FEEDBACK POTENTIOMETER LOW SIDE RESISTANCE


Measure the resistance between the EATC module C227 pin 9, circuit 438 (RD/WH) and the EATC module C281 pin 5, circuit 435 (YE/LB).

� Is the resistance between 250 and 1,500 ohms?

Yes GO to E16.

No GO to E14.

E14 CHECK CIRCUIT 435 (YE/LB) FOR AN OPEN


Measure the resistance between the EATC module C281 pin 5, circuit 435 (YE/LB) and the recirculation door actuator C208 pin 4, circuit 435 (YE/LB).




Yes GO to E15.

No REPAIR circuit 435 (YE/LB) for an open. CLEAR the DTCs. REPEAT the self-test.

E15 CHECK CIRCUIT 435 (YE/LB)

Measure the resistance between the EATC module C281 pin 5, circuit 435 (YE/LB) and ground.



No REPAIR circuit 435 (YE/LB). CLEAR the DTCs. REPEAT the self-test.

E16 CHECK THE FEEDBACK POTENTIOMETER HIGH SIDE RESISTANCE


Measure the resistance between the EATC module C281 pin 6, circuit 436 (RD/LG) and the EATC module C281 pin 5, circuit 435 (YE/LB).


Yes GO to E17.

No INSTALL a new recirculation door actuator. CLEAR the DTCs. REPEAT the self-test.

E17 CHECK CIRCUIT 436 (RD/LG) FOR A SHORT TO GROUND

Measure the resistance between the EATC module C281 pin 6, circuit 436 (RD/LG) and ground.


Yes GO to E18.



PINPOINT TEST F: NO COMMUNICATION WITH THE ELECTRONIC AUTOMATIC TEMPERATURE CONTROL MODULE


E18 CHECK CIRCUIT 438 (RD/WH) FOR A SHORT TO GROUND

Measure the resistance between the EATC module C227 pin 9, circuit 438 (RD/WH) and ground.


Yes GO to E19.


E19 CHECK CIRCUIT 435 (YE/LB) FOR A SHORT TO GROUND

Measure the resistance between the EATC module C281 pin 5, circuit 435 (YE/LB) and ground.



No REPAIR circuit 435 (YE/LB). CLEAR the DTCs. REPEAT the self-test.


F1 CHECK CIRCUIT 57 (BK) FOR AN OPEN

EATC Module C281

Measure the resistance between the EATC module C281 pin 3, circuit 57 (BK) and ground.


Yes GO to F2.

No REPAIR circuit 57 (BK). TEST the system for normal operation.

F2 CHECK CIRCUIT 729 (RD/WH)

Measure the voltage between the EATC module C281 pin 2, circuit 729 (RD/WH) and ground.



PINPOINT TEST G: THE EATC SYSTEM IS INOPERATIVE, INTERMITTENT OR INCORRECT OPERATION

� Is the voltage greater than 10 volts?

Yes GO to F3.

No REPAIR circuit 729 (RD/WH). TEST the system for normal operation.

F3 CHECK CIRCUIT 1040 (RD/BK)

Measure the voltage between the EATC module C281 pin 16, circuit 1040 (RD/BK) and ground.


Yes GO to Module Communication Network Diagnostics in Section 418-00 to diagnose the network concern.

No REPAIR circuit 1040 (RD/BK). TEST the system for normal operation.


G1 VERIFY AUTOMATIC OPERATION

Press the AUTOMATIC button.

� Does AUTO and the selected temperature appear in the display window?

Yes GO to G2.

No GO to G11.

G2 CARRY OUT THE EATC MODULE SELF-TEST

Carry out the EATC module self-test. Refer to the Electronic Automatic Temperature Control Module Self-Test in this section. Record the DTCs displayed, if any.

� Were any DTCs displayed as a result of the EATC self-test?

Yes REFER to the Electronic Automatic Temperature Control (EATC) Module Diagnostic Trouble Code (DTC) Index. CARRY OUT the necessary diagnosis and REPAIR as required.

No GO to G3.

G3 CHECK THE VACUUM FLUORESCENT DISPLAY



Exit self-test by pressing the DEFROST button. Observe the function symbols displayed on the vacuum fluorescent display.

� Is the display correct and complete without any missing elements?

Yes GO to G4.

No INSTALL a new EATC module. TEST the system for normal operation.

G4 CHECK THE BLOWER MANUAL OVERRIDE OPERATION

Slowly adjust the blower motor speed override control from LO to HI.

� Does the blower motor speed increase smoothly from low speed to high speed?

Yes GO to G5.

No If the blower motor is inoperative, GO to Pinpoint Test M. If the blower motor does not operate correctly, GO to Pinpoint Test N.

G5 VERIFY THE DEFROST OVERRIDE OPERATION

Press the override button for DEFROST operation.

� Is outside air being discharged from the windshield defroster nozzle and the side window demisters?

Yes GO to G6.

No GO to Pinpoint Test H.

G6 VERIFY THE FLOOR OVERRIDE OPERATION

Press the override button for FLOOR operation.

� Is outside air being discharged from the floor duct?

Yes GO to G7.


G7 VERIFY THE VENT OVERRIDE OPERATION

Press the override button for VENT operation.

� Is outside air being discharged from the instrument panel registers?

Yes GO to G8.


G8 VERIFY THE A/C CLUTCH DOES NOT ENGAGE IN THE VENT MODE

Press the override button for VENT operation.

� Does the A/C clutch engage when the VENT override button is pressed?

Yes REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.

No GO to G9.

G9 VERIFY THE MAX A/C OVERRIDE OPERATION

Make sure the ambient air temperature is above 5°C (41°F).

Press the override button for MAX A/C operation.

� Is recirculated air being discharged from the instrument panel registers?

Yes GO to G10.


G10 VERIFY A/C CLUTCH ENGAGEMENT IN THE MAX A/C MODE

Press the override button for MAX A/C operation.

� Does the A/C clutch engage when the MAX A/C override button is pressed?

Yes The test is complete. The system is functioning normally.



No GO to Pinpoint Test J.

G11 CHECK THE EATC MODULE FUNCTIONS

Press each function button and observe the display.

� Does the EATC carry out and display any functions?


No GO to G12.

G12 CHECK CIRCUIT 57 (BK) FOR AN OPEN

EATC Module C281



Yes GO to G13.


G13 CHECK CIRCUIT 729 (RD/WH)



Yes GO to G14.


G14 CHECK THE GROUND CIRCUIT TO THE EATC





PINPOINT TEST H: INCORRECT/ERRATIC DIRECTION OF AIRFLOW FROM OUTLET

Yes INSTALL a new EATC module (19980). TEST the system for normal operation.

No REPAIR circuit 57 (BK) for an open. TEST the system for normal operation.


H1 CHECK THE SYSTEM AIRFLOW

Adjust the blower motor speed to maximum. Check for correct airflow for each manual override button at engine idle speed.

� Is there airflow only from the defroster outlets only?

Yes GO to H2.

No GO to H16.

H2 CHECK FOR A DISCONNECTED SUPPLY HOSE

Check for a disconnected vacuum supply hose at the engine intake manifold, the A/C vacuum check valve, and the power brake booster.

� Is a vacuum hose disconnected?

Yes RECONNECT the vacuum hose. TEST the system for normal operation.

No GO to H3.

H3 CHECK FOR VACUUM AT THE SUPPLY HOSE

Vacuum Supply Hose

Check for vacuum at the vacuum supply hose.

� Is vacuum present at the vacuum supply hose?

Yes GO to H5.

No GO to H4.

H4 CHECK THE VACUUM SUPPLY HOSE FOR BLOCKAGE



Intake Manifold Vacuum Supply Hose

Connect a vacuum pump to the supply hose and try to pull a vacuum. If the pump can pull a vacuum, the hose is plugged. If the pump pulls a partial vacuum, the hose is restricted.

� Is the vacuum supply hose plugged or restricted?

Yes INSTALL a new vacuum supply hose. TEST the system for normal operation.

No REPAIR the vacuum supply port at the engine. TEST the system for normal operation.

H5 CHECK FOR VACUUM AT THE PLENUM HARNESS CONNECTOR

Power Brake Booster Hose

Plenum Vacuum Harness

Check for vacuum at the plenum vacuum harness connector.

� Is vacuum present at the plenum vacuum harness connector black hose?

Yes GO to H14.

No GO to H6.

H6 CHECK THE VACUUM SYSTEM

Intake Manifold Vacuum Supply Hose

Connect a vacuum pump to the supply hose and try to pull a vacuum. If the pump can pull a vacuum, the vacuum system is plugged. If the pump pulls a partial vacuum, the system is restricted.

� Is the vacuum system plugged or restricted?



Yes GO to H7.

No GO to H9.

H7 CHECK THE PLENUM VACUUM HARNESS FOR BLOCKAGE

Disconnect the plenum vacuum harness from the vacuum reservoir tank.

Connect a vacuum pump to the black hose of the plenum vacuum harness and try to pull a vacuum. If the pump can pull a vacuum, the plenum harness is plugged. If the pump pulls a partial vacuum, the plenum harness is restricted.

� Is the plenum vacuum harness plugged or restricted?

Yes INSTALL a new plenum vacuum harness. TEST the system for normal operation.

No GO to H8.

H8 CHECK THE A/C VACUUM CHECK VALVE FOR BLOCKAGE

A/C Vacuum Check Valve

Plug one port of the A/C vacuum check valve, connect a vacuum pump to the other port and try to pull a vacuum. If the pump can pull a vacuum, the check valve is plugged. If the pump pulls a partial vacuum, the check valve is restricted.

� Is the A/C vacuum check valve plugged or restricted?

Yes INSTALL a new A/C vacuum check valve. TEST the system for normal operation.

No INSTALL a new vacuum reservoir. TEST the system for normal operation.

H9 CHECK THE BRAKE BOOSTER FOR LEAKAGE

Power Brake Booster Hose

Plenum Vacuum Harness

Plug the power brake booster hose and leak test the system with a vacuum pump at the intake manifold end.



� Does the vacuum system leak?

Yes GO to Section 206-07 to repair a leaking power brake booster.

No GO to H10.

H10 CHECK THE AUTOMATIC PARKING BRAKE RELEASE FOR LEAKAGE

Automatic Parking Brake Release Hose

Plug the automatic parking brake release hose port on the vacuum reservoir tank and leak test the system with a vacuum pump at the intake manifold vacuum supply hose.

� Does the vacuum system leak?

Yes GO to Section 206-05 to repair a leaking automatic parking brake release system.

No GO to H11.

H11 CHECK THE VACUUM RESERVOIR TANK FOR LEAKAGE

A/C Vacuum Reservoir Tank

Leak test the A/C vacuum reservoir tank with a vacuum pump.

� Does the A/C vacuum reservoir tank leak?

Yes INSTALL a new A/C vacuum reservoir tank. TEST the system for normal operation.

No GO to H12.

H12 CHECK THE VACUUM CHECK VALVE FOR LEAKAGE



A/C Vacuum Check Valve

Connect the A/C vacuum check valve to a vacuum tester.

Apply 51 kPa (15 inches-Hg) of vacuum to the A/C vacuum check valve and observe the gauge reading.

If the vacuum loss exceeds 3.37 kPa (1 inch-Hg) per minute, remove the A/C vacuum check valve from the tester and plug the vacuum hose. Pull a vacuum with the tester to be certain that the hose and tester are not the cause of the leak.

� Does the A/C vacuum check valve lose more than 3.37 kPa (1 inch-Hg) of vacuum in one minute?

Yes INSTALL a new A/C vacuum check valve (19A563). TEST the system for normal operation.

No GO to H13.

H13 CHECK THE PLENUM VACUUM HARNESS FOR LEAKAGE

Plug the plenum vacuum harness.

Leak test the plenum vacuum harness with a vacuum pump.

� Does the plenum vacuum harness leak?

Yes INSTALL a new plenum vacuum harness. TEST the system for normal operation.

No GO to H14.

H14 CHECK THE EATC VACUUM HARNESS FOR LEAKAGE

EATC Vacuum Harness

Plug the black hose and leak test the vacuum harness with a vacuum pump.



� Does the vacuum harness leak?

Yes REPAIR the EATC vacuum harness. TEST the system for normal operation.

No GO to H15.

H15 CHECK THE EATC VACUUM HARNESS FOR BLOCKAGE

Remove the plug from the black hose.

Connect a vacuum pump to the black hose and try to pull a vacuum. If the vacuum pump can pull a vacuum, the hose is plugged. If the vacuum pump pulls a partial vacuum, the hose is restricted.

� Is the hose plugged or restricted?

Yes INSTALL a new vacuum harness. TEST the system for normal operation.


H16 CHECK THE VACUUM CONTROL MOTOR LINE FOR BLOCKAGE

Disconnect the EATC module vacuum connector.

Disconnect the vacuum line from the appropriate vacuum control motor noted in Step H1.

Connect a vacuum pump to the appropriate vacuum control motor line noted in Step H1, and attempt to pull a vacuum.

� Can a vacuum be pulled on the vacuum control motor line?

Yes REPAIR or INSTALL a new plenum vacuum harness. TEST the system for normal operation.

No GO to H17.

H17 CHECK THE VACUUM CONTROL MOTOR LINE FOR LEAKS

Plug the vacuum control motor line at the vacuum control motor connection.

Leak test the vacuum control motor line using the vacuum pump.



PINPOINT TEST I: INSUFFICIENT, ERRATIC, OR NO HEAT

� Does the vacuum control motor line leak?

Yes REPAIR or INSTALL a new vacuum harness. TEST the system for normal operation.

No GO to H18.

H18 CHECK THE VACUUM CONTROL MOTOR FOR LEAKS AND CORRECT OPERATION

Connect the vacuum pump to the appropriate vacuum control motor and pull a vacuum.

� Does the vacuum control motor operate and hold vacuum?

Yes GO to H19.

No INSTALL a new vacuum control motor. TEST the system for normal operation.

H19 CHECK THE MODE DOOR LINKAGE AND MOVEMENT

Inspect the mode door linkage and verify correct movement of the mode door.

� Is the mode door or mode door linkage broken, binding or otherwise obstructed?

Yes REPAIR the mode door or mode door linkage as necessary. TEST the system for normal operation.



I1 CHECK FOR CORRECT ENGINE COOLANT LEVEL

Check the engine coolant level when HOT and when COLD.

� Is the engine coolant at the correct level (hot and cold)?

Yes GO to I2.

No GO to I3.



I2 CHECK FOR HOT WATER TO THE HEATER CORE INLET HOSE

WARNING: The heater core inlet hose will become too hot to handle and can cause serious burns if the system is working correctly.

Start Engine

Allow the engine to reach normal operating temperature.

Feel the heater core inlet hose.

� Is the heater core inlet hose too hot to handle?

Yes GO to I4.

No GO to Section 303-03 to check the cooling system function.

I3 CHECK THE COOLANT SYSTEM INCLUDING THE RADIATOR CAP FOR LEAKS

Fill the engine cooling system to the specified level.

Pressure check the engine cooling system, including the radiator cap. Refer to Section 303-03. It is not necessary to check the components separately at this time.

� Does the engine cooling system, including the radiator cap, hold pressure?

Yes GO to I4.

No REPAIR the cooling system leak. TEST the system for normal operation.

I4 CHECK THE HEATER CORE OUTLET HOSE FOR HOT WATER

WARNING: The heater core outlet hose will become too hot to handle and can cause serious burns if the system is working correctly.

Allow the engine to reach normal operating temperature.

Feel the heater core outlet hose.

� Is the heater core outlet hose cool or cold?

Yes CARRY OUT the Heater Core Component Test. Refer to Heater Core under Component Tests in this section to determine whether a plugged or partially plugged condition exists.



PINPOINT TEST J: THE AIR CONDITIONING (A/C) IS INOPERATIVE/DOES NOT OPERATE CORRECTLY

No GO to Pinpoint Test A.


J1 CHECK THE PID WACF WITH THE A/C OFF

NOTE: When PCM PID WACF is YES, this is the same fault as DTC P1460.

Press the OFF button on the EATC module.

PCM PID WACF

� Does the PCM PID WACF read YES?

Yes REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual to continue the diagnosis.

No GO to J2.

J2 CHECK THE PID WACF WITH THE A/C ON

NOTE: When PCM PID WACF is YES, this is the same fault as DTC P1460.

Start the engine and run at idle.

Press the MAX A/C manual override button on the EATC module.

PCM PID WACF


Yes REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual to continue the diagnosis.

No GO to J3.

J3 CHECK THE PID ACCS WITH THE A/C ON

PCM PID ACCS

� Does the PCM PID ACCS read ON?

Yes GO to J4.

No GO to J5.

J4 CHECK THE PID WAC WITH THE A/C ON

PCM PID WAC

� Does the PID WAC read ON?

Yes GO to J18.

No REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual to continue the diagnosis.

J5 CHECK THE INPUT TO THE PCM

NOTE: Do not directly probe the PCM wire harness connector.



Powertrain Control Module C185

Connect the EEC-V 104-Pin Breakout Box to the PCM C185. Do not connect the breakout box to the PCM.

Press the MAX A/C manual override button on the EATC module.

Measure the voltage at breakout box pin 41, circuit 347 (BK/YE).


Yes INSTALL a new powertrain control module. Refer to Section 303-14. TEST the system for normal operation.

No GO to J6.

J6 CHECK THE REFRIGERANT SYSTEM PRESSURE

Connect the manifold gauge set to the service ports. Refer to Manifold Gauge Set Connection in this section.

� Is the pressure reading between 345 kPa (50 psi) and 1,724 kPa (250 psi)?

Yes GO to J7.

No CHECK the system for refrigerant system leaks. Refer to Leak Detection—Using the Refrigerant Leak Detector or Leak Detection—Using Tracer Dye in this section.

J7 CHECK THE FUSE JUNCTION PANEL FUSE 6 (15A)

Fuse Junction Panel Mini Fuse 6 (15A)

� Is the mini fuse 6 (15A) open?

Yes GO to J8.

No GO to J14.

J8 CHECK CIRCUIT 347 (BK/YE) FOR A SHORT TO GROUND

Powertrain Control Module C185

A/C Pressure Cutoff Switch C126

Measure the resistance between the A/C pressure cutoff switch C126, circuit 347 (BK/YE) and ground.




Yes GO to J9.

No REPAIR circuit 347 (BK/YE). TEST the system for normal operation.

J9 CHECK THE A/C HIGH PRESSURE CUTOFF SWITCH

A/C Cycling Switch C155


Measure the resistance between the A/C cycling switch C155, circuit 883 (PK/LB) and ground.


Yes GO to J11.

No GO to J10.

J10 CHECK CIRCUIT 883 (PK/LB)

A/C Pressure Cutoff Switch

Measure the resistance between A/C cycling switch C155, circuit 883 (PK/LB) and ground.


Yes INSTALL a new A/C pressure cutoff switch. TEST the system for normal operation.

No REPAIR circuit 883 (PK/LB). TEST the system for normal operation.

J11 CHECK CIRCUIT 1040 (RD/BK) FOR A SHORT



A/C Clutch Relay

Measure the resistance between the A/C cycling switch C155, circuit 1040 (RD/BK) and ground.


Yes GO to J12.


J12 CHECK THE A/C CYCLING SWITCH


Measure the resistance between the A/C clutch relay socket pin 3, circuit 1040 (RD/BK) and ground.


Yes GO to J13.

No INSTALL a new A/C cycling switch. TEST the system for normal operation.

J13 CHECK CIRCUIT 321 (GY/WH) FOR A SHORT

A/C Clutch Field Coil C156

Measure the resistance between A/C clutch field coil C156, circuit 321 (GY/WH) and ground.


Yes INSTALL a new A/C clutch field coil. TEST the system for normal operation.

No REPAIR circuit 321 (GY/WH). TEST the system for normal operation.

J14 CHECK POWER TO THE A/C CYCLING SWITCH

Install a new mini fuse 6 (15A).




Measure the voltage between the A/C cycling switch C155, circuit 1040 (RD/BK) and ground.


Yes GO to J15.


J15 BYPASS THE A/C CYCLING SWITCH

PCM C185

Connect a fused jumper lead between the A/C cycling switch C155, circuit 1040 (RD/BK) and circuit 883 (PK/LB).

PCM PID ACCS


Yes INSTALL a new A/C cycling switch. TEST the system for normal operation.

No GO to J16.

J16 CHECK CIRCUIT 883 (PK/LB) FOR AN OPEN

PCM C185




Measure the voltage between the A/C pressure cutoff switch C126, circuit 883 (PK/LB) and ground.


Yes GO to J17.

No REPAIR circuit 883 (PK/LB). TEST the system for normal operation.

J17 BYPASS THE A/C PRESSURE CUTOFF SWITCH

Connect a fused jumper lead between the A/C pressure cutoff switch C126, circuit 883 (PK/LB) and circuit 347 (BK/YE).

PCM C185

PCM PID ACCS


Yes INSTALL a new A/C pressure cutoff switch. TEST the system for normal operation.

No REPAIR circuit 347 (BK/YE) for an open. TEST the system for normal operation.

J18 CHECK CIRCUIT 1040 (RD/BK) FOR AN OPEN

A/C Clutch Relay



Measure the voltage between the A/C clutch relay socket pin 3, circuit 1040 (RD/BK) and ground.


Yes GO to J19.


J19 CHECK THE A/C CLUTCH INPUT

A/C Clutch Relay


In Active Command Mode, command the PCM outputs ON.

Measure the voltage between the A/C clutch field coil C156, circuit 321 (GY/WH) and ground.


Yes GO to J21.

No GO to J20.

J20 CHECK CIRCUIT 321 (GY/WH) FOR AN OPEN

A/C Clutch Relay

Measure the resistance between the A/C clutch relay socket pin 5, circuit 321 (GY/WH) and the A/C clutch field coil C156, circuit 321 (GY/WH).



PINPOINT TEST K: THE AIR CONDITIONING (A/C) IS ALWAYS ON


Yes INSTALL a new A/C clutch relay. CLEAR the DTCs. TEST the system for normal operation.

No REPAIR circuit 321 (GY/WH). CLEAR the DTCs. TEST the system for normal operation.

J21 CHECK THE A/C CLUTCH GROUND CIRCUIT FOR AN OPEN

Measure the resistance between the A/C clutch field coil C156, circuit 57 (BK) and ground.


Yes INSTALL a new A/C clutch field coil. CLEAR the DTCs. TEST the system for normal operation.

No REPAIR circuit 57 (BK) for an open. CLEAR the DTCs. TEST the system for normal operation.


K1 CHECK THE PID WACF WITH THE A/C OFF

Press the OFF button on the EATC module.

PCM PID WACF


Yes REPAIR circuit 73 (OG/LB). CLEAR the DTCs. TEST the system for normal operation.

No GO to K2.

K2 CHECK CIRCUIT 321 (GY/WH) FOR A SHORT TO B+




PINPOINT TEST L: THE STEERING WHEEL CONTROL SWITCH IS INOPERATIVE/DOES NOT OPERATE CORRECTLY

In the Active Command Mode, command PCM outputs OFF.



Yes GO to K3.

No CHECK the A/C clutch air gap. Refer to A/C Clutch Air Gap Adjustment in this section. CLEAR the DTCs. TEST the system for normal operation.

K3 CHECK THE A/C CLUTCH RELAY

A/C Clutch Relay



Yes REPAIR circuit 321 (GY/WH). CLEAR the DTCs. TEST the system for normal operation.

No INSTALL a new A/C clutch relay. CLEAR the DTCs. TEST the system for normal operation.


L1 CHECK THE EATC MODULE INPUT CIRCUIT

EATC Module C227

Measure the resistance between the EATC module C227 pin 8, circuit 1070 (BN/LB) and ground.




Yes GO to L2.

No If the resistance is less than 4,500 ohms, GO to L3 . If the resistance is greater than 5,000 ohms, GO to L6 .

L2 CHECK THE STEERING WHEEL CONTROL SWITCH

Measure the resistance between the EATC module C227 pin 8, circuit 1070 (BN/LB) and ground while pressing each of the steering wheel control switch buttons. Note the resistance and refer to the table below.

Button Resistance

Temp UP 336-375 ohms

Temp DOWN 1,620-1,810 ohms

Fan UP 736-821 ohms

Fan DOWN 123-138 ohms

� Are the resistances within the ranges indicated?


No INSTALL a new steering wheel control switch. TEST the system for normal operation.

L3 CHECK THE STEERING WHEEL CONTROL SWITCH FOR AN INTERNAL SHORT

Steering Wheel Control Switch Connector



Yes INSTALL a new steering wheel control switch. TEST the system for normal operation.

No GO to L4.

L4 CHECK CIRCUIT 1070 (BN/LB) FOR A SHORT TO GROUND

Clockspring C283M and C283F





Yes GO to L5.

No REPAIR circuit 1070 (BN/LB). TEST the system for normal operation.

L5 CHECK THE CLOCKSPRING FOR A SHORT TO GROUND





Yes REPAIR or INSTALL a new steering wheel wiring harness. TEST the system for normal operation.

No INSTALL a new clockspring. TEST the system for normal operation.

L6 CHECK THE STEERING WHEEL CONTROL SWITCH GROUND

Steering Wheel Control Switch Connector

Measure the resistance between the steering wheel control switch connector pin 3 (BK) and ground.


Yes GO to L7.

No GO to L9.

L7 CHECK CIRCUIT 1070 (BN/LB) FOR AN OPEN




Measure the resistance between the EATC module C227 pin 8, circuit 1070 (BN/LB) and the clockspring C283F pin 2, circuit 1070 (BN/LB).


Yes GO to L8.

No REPAIR circuit 1070 (BN/LB). TEST the system for normal operation.

L8 CHECK THE CLOCKSPRING FOR AN OPEN


Measure the resistance between the clockspring C238F pin 2 (OG/BK) and the clockspring C283M pin 2 (OG/BK).


Yes REPAIR or INSTALL a new steering wheel wiring harness. TEST the system for normal operation.

No INSTALL a new clockspring. TEST the system for normal operation.

L9 CHECK CIRCUIT 848 (DG/OG)


Measure the resistance between the clockspring C283F pin 1, circuit 848 (DG/OG) and ground.


Yes GO to L12.

No GO to L10.

L10 CHECK CIRCUIT 848 (DG/OG) FOR AN OPEN



PINPOINT TEST M: THE BLOWER MOTOR IS INOPERATIVE

Speed Control Module C123

Measure the resistance between the speed control module C123 pin 6, circuit 848 (DG/OG) and the clockspring C283F pin 1, circuit 848 (DG/OG).


Yes GO to L11.

No REPAIR circuit 848 (DG/OG). TEST the system for normal operation.

L11 CHECK CIRCUIT 676 (PK/OG)

Measure the resistance between the speed control module C123 pin 10, circuit 676 (PK/OG) and ground.


Yes INSTALL a new speed control module. TEST the system for normal operation.

No REPAIR circuit 676 (PK/OG). TEST the system for normal operation.

L12 CHECK THE STEERING WHEEL WIRING HARNESS


Measure the resistance between the steering wheel control switch connector pin 3 (BK) and the clockspring C238M pin 4 (BK).


Yes INSTALL a new clockspring. TEST the system for normal operation.

No REPAIR or INSTALL a new steering wheel wiring harness. TEST the system for normal operation.


M1 VERIFY THE BLOWER MOTOR OPERATION



Press the PANEL button on the EATC module. Adjust the blower motor setting to LO and then to HI.

� Is the blower motor inoperative in all settings?

Yes GO to M2.

No GO to Pinpoint Test N.

M2 CHECK FOR VOLTAGE TO THE BLOWER MOTOR

Blower Motor C167

Measure the voltage between the blower motor C167, circuit 181 (BR/OG) and ground.


Yes GO to M3.

No REPAIR circuit 181 (BR/OG). TEST the system for normal operation.

M3 CHECK THE BLOWER MOTOR

Blower Motor C167

Blower Motor Speed Control C169

Connect a fused jumper lead between the blower motor speed control C169 pin 4, circuit 515 (OG/RD) and C169 pin 5, circuit 57 (BK).



� Does the blower motor operate?

Yes GO to M6.

No INSTALL a new blower motor. TEST the system for normal operation.GO to M4.

M4 CHECK CIRCUIT 57 (BK)

Remove the fused jumper lead from the blower motor speed control C169.

Measure the resistance between the blower motor speed control C169 pin 5, circuit 57 (BK) and ground.


Yes GO to M5.


M5 CHECK CIRCUIT 515 (OG/RD)

Blower Motor C167

Measure the resistance between the blower motor C167, circuit 515 (OG/RD) and the blower motor speed control C169 pin 4, circuit 515 (OG/RD).


Yes INSTALL a new blower motor. TEST the system for normal operation.

No REPAIR circuit 515 (OG/RD). TEST the system for normal operation.

M6 CHECK THE EATC MODULE OUTPUT

Remove the fused jumper lead from the blower motor speed control C169.


Adjust the blower motor speed to HI.

Measure the voltage between the EATC module C227 pin 24, circuit 754 (LG/WH) and ground by back-probing the EATC module C227.



PINPOINT TEST N: THE BLOWER MOTOR DOES NOT OPERATE CORRECTLY

� Is the voltage within 2 volts of battery voltage?

Yes GO to M7.


M7 CHECK CIRCUIT 754 (LG/WH) FOR AN OPEN OR SHORT TO GROUND


EATC Module C227

Measure the resistance between the EATC module C227 pin 24, circuit 754 (LG/WH) and the blower motor speed control C169 pin 3, circuit 754 (LG/WH), and measure the resistance between the EATC module C227 pin 24, circuit 261 (OG/BK) and ground.

� Is the resistance less than 5 ohms between the EATC module and the blower motor speed control and

greater than 10,000 ohms between the EATC module and ground?

Yes INSTALL a new blower motor speed control. TEST the system for normal operation.

No REPAIR circuit 754 (LG/WH). TEST the system for normal operation.


N1 CHECK CIRCUIT 515 (OG/RD) FOR A SHORT TO GROUND


Press the PANEL button on the EATC module. Adjust the blower motor setting to LO and then to HI.

� Does the blower motor operate correctly?

Yes



REPAIR circuit 515 (OG/RD) for a short to ground. TEST the system for normal operation.

No GO to N2.

N2 CHECK THE BLOWER MOTOR SPEED CONTROL


EATC Module C227

� Does the blower motor operate?


No GO to N3.

N3 CHECK THE BLOWER MOTOR SPEED CONTROL CIRCUITS FOR AN OPEN


Measure the resistance between the blower motor speed control C169:

� pin 1, circuit 269 (LB/OG) and the EATC module C227 pin 10. � pin 2, circuit 752 (YE/RD) and the EATC module C227 pin 23. � pin 3, circuit 754 (LG/WH) and the EATC module C227 pin 24.

� Are the resistances less than 5 ohms?

Yes GO to N4.

No REPAIR the affected circuit. TEST the system for normal operation.

N4 CHECK THE BLOWER MOTOR SPEED CONTROL CIRCUITS FOR A SHORT TO VOLTAGE

Measure the voltage between the blower motor speed control C169:

� pin 1, circuit 269 (LB/OG) and ground. � pin 2, circuit 752 (YE/RD) and ground. � pin 3, circuit 754 (LG/WH) and ground.




Yes REPAIR the affected circuit. TEST the system for normal operation.

No GO to N5.

N5 CHECK THE BLOWER MOTOR SPEED CONTROL CIRCUITS FOR A SHORT TO GROUND


� pin 1, circuit 269 (LB/OG) and ground. � pin 2, circuit 752 (YE/RD) and ground. � pin 3, circuit 754 (LG/WH) and ground.


Yes GO to N6.

No REPAIR the affected circuit. TEST the system for normal operation.

N6 CHECK THE BLOWER MOTOR SPEED CONTROL CIRCUITS FOR SHORTS


� pin 2, circuit 752 (YE/RD) and C169 pin 3, circuit 754 (LG/WH). � pin 2, circuit 752 (YE/RD) and C169 pin 1, circuit 269 (LB/OG). � pin 3, circuit 754 (LG/WH) and C169 pin 1, circuit 269 (LB/OG).


Yes GO to N7.

No REPAIR the affected circuits. TEST the system for normal operation.

N7 CHECK THE EATC MODULE HIGH BLOWER OUTPUT

EATC C281


Adjust the blower motor speed to HI.

Measure the voltage between the EATC module C227 pin 24, circuit 754 (LG/WH) and ground by back-probing the EATC module C227.



PINPOINT TEST O: THE TEMPERATURE SET POINT DOES NOT REPEAT AFTER TURNING THE IGNITION SWITCH OFF

� Is the voltage within 2 volts of battery voltage?

Yes GO to N8.


N8 CHECK THE EATC MODULE BLOWER CONTROL OUTPUT

Adjust the blower motor speed to LO.

Measure the voltage between the EATC module C227 pin 23, circuit 752 (YE/RD) and ground by back-probing the EATC module C227.

� Is the voltage greater than 1 volt?




O1 CHECK THE MEMORY BACKUP SUPPLY TO THE EATC MODULE

EATC Module C281




No GO to O2.

O2 CHECK CIRCUIT 729 (RD/WH) FOR AN OPEN



PINPOINT TEST P: THE TEMPERATURE DISPLAY WILL NOT SWITCH BETWEEN CELSIUS AND FAHRENHEIT

Fuse Junction Panel Fuse 19 (10A)

Measure the resistance between the fuse junction panel fuse 19 cavity, circuit 729 (RD/WH) and the EATC module C281 pin 2, circuit 729 (RD/WH).





P1 CHECK THE EATC °C TO °F DISPLAY


Press the MAX A/C and FRONT DEFROST manual override buttons on the EATC module simultaneously for at least 0.75 second.

� Did the display vary between °C and °F?

Yes GO to P2.


P2 CHECK THE ENGLISH/METRIC FUNCTION

Select the E/M item on the message center.

Press the reset button.



PINPOINT TEST Q: THE REAR AUDIO/CLIMATE CONTROL SWITCH IS INOPERATIVE/DOES NOT OPERATE CORRECTLY

� Did the EATC module display vary between °C and °F?

Yes The system is functioning correctly.

No GO to the Module Communication Network Diagnostics in Section 418-00.


Q1 CARRY OUT THE AUDIO CONTROL MODULE (ACM) SELF-TEST

Carry out the audio control module (ACM) audio internal/external self-test. Refer to Section 415-00.

� Is DTC U2005 present?

Yes GO to Q6.

No GO to Q2.

Q2 CHECK THE REAR AUDIO/CLIMATE CONTROL SWITCH GROUND

Rear Audio/Climate Control Switch C374

Measure the resistance between the rear audio/climate control switch C374 pin 5, circuit 676 (PK/OG) and ground.


Yes GO to Q3.


Q3 CHECK THE VOLTAGE TO THE REAR AUDIO/CLIMATE CONTROL SWITCH CIRCUIT 583 (YE)

Measure the voltage between the rear audio/climate control switch C374 pin 1, circuit 583 (YE) and ground.




Yes GO to Q4.

No GO to Q10.

Q4 CHECK THE VOLTAGE TO THE REAR AUDIO/CLIMATE CONTROL SWITCH CIRCUIT 595 (LB/RD)

Measure the voltage between the rear audio/climate control switch C374 pin 2, circuit 595 (LB/RD) and ground.

� Is the voltage approximately 5 volts?

Yes GO to Q5.

No GO to Q11.

Q5 CHECK THE REAR AUDIO/CLIMATE CONTROL MODULE INPUT SIGNAL

Rear Audio/Climate Control Switch C374

NOTE: Carry out the following step multiple times to determine if the command signal is present.

NOTE: Using an oscilloscope will give a clearer indication of activity when monitoring this circuit.

Measure the voltage between the rear audio/climate control module C368 pin 7, circuit 595 (LB/RD) and ground by back-probing the rear audio/climate control module C368 pin 7, circuit 595 (LB/RD). Press and hold a climate control button on the rear audio/climate control switch.

� Does the voltage measure approximately 4.5 to 5.0 volts and then drop when a climate control button is

depressed?

Yes GO to Q8.

No INSTALL a new rear audio/climate control switch. TEST the system for normal operation.

Q6 CHECK THE ACP-A SIGNAL TO THE ACM

NOTE: Activity on the ACP bus is reduced with the ignition switch in the accessory position.





Measure the voltage between the ACM C258 pin 7, circuit 833 (TN) and ground by back-probing the ACM C258 pin 7, circuit 833 (TN). Press and hold a climate control button on the rear audio/climate control switch.

� Does the voltage measure approximately 400 millivolts and increase when a climate control button is

depressed?

Yes GO to Q7.

No GO to Q14.

Q7 CHECK THE ACP-B SIGNAL TO THE ACM

NOTE: Activity on the ACP bus is reduced with the ignition switch in the accessory position.



Measure the voltage between the ACM C258 pin 6, circuit 832 (LB/PK) and ground by back-probing the ACM C258 pin 6, circuit 832 (LB/PK). Press and hold a climate control button on the rear audio/climate control switch.

� Does the voltage measure approximately 4.5 volts and decrease when a climate control button is

depressed?

Yes INSTALL a new audio control module (ACM). TEST the system for normal operation.

No GO to Q17.

Q8 CHECK THE SCP BUS

NOTE: Activity on the SCP bus is reduced with the ignition switch in the accessory position.

Measure the voltage between the ACM C258 pin 3, circuit 914 (TN/OG) and ground by back-probing the ACM C258 pin 3, circuit 914 (TN/OG). The voltage should measure approximately 7 millivolts.

Measure the voltage between the ACM C258 pin 4, circuit 915 (PK/LB) and ground by back-probing the ACM C258 pin 4, circuit 915 (PK/LB). The voltage should measure approximately 4.5 volts.

� Are the voltage measurements as specified?

Yes GO to Q9.

No



REPAIR the network concern. REFER to Section 418-00.

Q9 CHECK THE SIGNAL FROM THE ACM

NOTE: Activity on the SCP bus is reduced with the ignition switch in the accessory position.



Measure the voltage between the ACM C258 pin 3, circuit 914 (TN/OG) and ground by back-probing the ACM C258 pin 3, circuit 914 (TN/OG). Press and hold a climate control button on the rear audio/climate control switch. The voltage should measure approximately 7 millivolts then slightly increase when a climate control button is depressed.



Measure the voltage between the ACM C258 pin 4, circuit 915 (PK/LB) and ground by back-probing the ACM C258 pin 4, circuit 915 (PK/LB). Press and hold a climate control button on the rear audio/climate control switch. The voltage should measure approximately 4.5 volts then slightly decrease when a climate control button is depressed.

� Are the voltage measurements as specified?


No INSTALL a new audio control module (ACM). TEST the system for normal operation.

Q10 CHECK CIRCUIT 583 (YE)

Rear Audio/Climate Control Module C368

Measure the resistance between the rear audio/climate control switch C374 pin 1, circuit 583 (YE) and the rear audio/climate control module C368 pin 16, circuit 583 (YE).


Yes GO to Q12.

No REPAIR circuit 583 (YE). TEST the system for normal operation.

Q11 CHECK CIRCUIT 595 (LB/RD)

Measure the resistance between the rear audio/climate control switch C374 pin 2, circuit 595 (LB/RD) and the rear audio/climate control module C368 pin 7, circuit 595 (LB/RD).




Yes GO to Q12.

No REPAIR circuit 595 (LB/RD). TEST the system for normal operation.

Q12 CHECK THE VOLTAGE TO THE REAR AUDIO/CLIMATE CONTROL MODULE


Measure the voltage between the rear audio/climate control module C368 pin 15, circuit 964 (DB/LG) and ground.


Yes GO to Q13.

No REPAIR circuit 964 (DB/LG). TEST the system for normal operation.

Q13 CHECK THE REAR AUDIO/CLIMATE CONTROL MODULE GROUND

Measure the resistance between the rear audio/climate control module C368 pin 5, circuit 676 (PK/OG) and ground.


Yes INSTALL a new rear audio/climate control module. TEST the system for normal operation.


Q14 CHECK CIRCUIT 833 (TN) FOR AN OPEN


Measure the resistance between the ACM C258 pin 7, circuit 833 (TN) and the rear audio/climate control module C368 pin 3, circuit 833 (TN).




Yes GO to Q15.

No REPAIR circuit 833 (TN). TEST the system for normal operation.

Q15 CHECK CIRCUIT 833 (TN) FOR A SHORT TO GROUND

Measure the resistance between the ACM C258 pin 7, circuit 833 (TN) and ground.


Yes GO to Q16.

No REPAIR circuit 833 (TN). TEST the system for normal operation.

Q16 CHECK CIRCUIT 833 (TN) FOR A SHORT TO VOLTAGE

Measure the voltage between the ACM C258 pin 7, circuit 833 (TN) and ground.


Yes REPAIR circuit 833 (TN). TEST the system for normal operation.

No INSTALL a new rear audio/climate control module. TEST the system for normal operation.

Q17 CHECK CIRCUIT 832 (LB/PK) FOR AN OPEN


Measure the resistance between the ACM C258 pin 6, circuit 832 (LB/PK) and the rear audio/climate control module C368 pin 10, circuit 832 (LB/PK).



Component Tests

Heater Core

WARNING: Carbon monoxide is colorless, odorless and dangerous. If it is necessary to operate the engine with the vehicle in a closed area such as a garage, always use an exhaust collector to vent the exhaust gases outside the closed area.

1. NOTE: Testing of returned heater cores reveals that a large percentage of heater cores are good and new heater cores were not required. If a heater core leak is suspected, the heater core must be tested by following the plugged heater core component test before the heater core pressure test. Carry out a system inspection by checking the heater system thoroughly as follows:

Inspect for evidence of coolant leakage at the heater water hose to heater core attachments. A coolant leak in the heater water hose could follow the heater core tube to the heater core and appear as a leak in the heater core.


Yes GO to Q18.

No REPAIR circuit 832 (LB/PK). TEST the system for normal operation.

Q18 CHECK CIRCUIT 832 (LB/PK) FOR A SHORT TO GROUND

Measure the resistance between the ACM C258 pin 6, circuit 832 (LB/PK) and ground.


Yes GO to Q19.

No REPAIR circuit 832 (LB/PK). TEST the system for normal operation.

Q19 CHECK CIRCUIT 832 (LB/PK) FOR A SHORT TO VOLTAGE

Measure the voltage between the ACM C258 pin 6, circuit 832 (LB/PK) and ground.


Yes REPAIR circuit 832 (LB/PK). TEST the system for normal operation.

No INSTALL a new rear audio/climate control module. TEST the system for normal operation.



2. NOTE: Spring-type clamps are installed as original equipment. Installation and overtightening of non-specification clamps can cause leakage at the heater water hose connection and damage the heater core.

Check the integrity of the heater water hose clamps.

Heater Core—Plugged

WARNING: The heater core inlet hose will become too hot to handle if the system is working correctly.

1. Check to see that the engine coolant is at the correct level.

2. Start the engine and turn on the heater.

3. When the engine coolant reaches operating temperature, feel the heater core outlet hose to see if it is hot. If it is not hot:

� the heater core can have an air pocket

� the heater core can be plugged, or

� the thermostat is not working correctly.

Heater Core—Pressure Test

Use the Radiator/Heater Core Pressure Tester to carry out the pressure test.

1. NOTE: Due to space limitations, a bench test may be necessary for pressure testing.

Drain the coolant from the cooling system.

2. Disconnect the heater water hoses from the heater core. For additional information, refer to Section 412-02.

3. Install a short piece of heater water hose, approximately 101 mm (4 inches) long on each heater core tube.

4. Fill the heater core and heater water hoses with water and install Plug BT-7422-B and adapter BT-7422-A from the radiator/heater core pressure tester in the heater water hose ends. Secure the heater water hoses, plug and adapter with hose clamps.

5. Attach the pump and gauge assembly from the Radiator/Heater Core Pressure Tester to the adapter.

6. Close the bleed valve at the base of the gauge. Pump 138 kPa (20 psi) of air pressure into the heater core.

7. Observe the pressure gauge for a minimum of three minutes.

8. If the pressure drops, check the heater water hose connections to the core tubes for leaks. If the heater water hoses do not leak, remove the heater core from the vehicle and carry out the bench test.

Heater Core—Bench Test

1. Remove the heater core from the vehicle. For additional information, refer to Section 412-02.

2. Drain all of the coolant from the heater core.

3. Connect a 101 mm (4 inch) test heater water hose with plug and adapter to each of the core tubes. Then connect the Radiator/Heater Core Pressure Tester to the adapter.

4. Apply 138 kPa (20 psi) of air pressure to the heater core. Submerge the heater core in water.

5. If a leak is observed, install a new heater core.

A/C Evaporator/Condenser Core—On-Vehicle Leak Test



1. Discharge and recover the refrigerant. For additional information, refer to Discharging and Recovery in this section.

2. NOTE: DO NOT leak test an A/C evaporator core with the suction accumulator/drier (19C836) attached to the core tubes.

Disconnect the suspect A/C evaporator core or A/C condenser core from the A/C system. For additional information, refer to Section 412-03.

3. Clean the spring lock couplings. For additional information, refer to Spring Lock Coupling in this section.

4. Connect the appropriate test fittings from the R12-/R134a Air Conditioning Test Fitting Set to the evaporator or condenser tube connections.

5. NOTE: The automatic shut-off valves on some gauge set hoses do not open when connected to the test fittings. If available, use hoses without shut-off valves. If hoses with shut-off valves are used, make sure the valve opens when attached to the test fittings or install an adapter which will activate the valve. The test is not valid if the shut-off valve does not open.

Connect the red and blue hoses from the R134-a Manifold Gauge Set to the test fittings on the A/C evaporator core or A/C condenser core. Connect the yellow hose to a known good vacuum pump.

6. Open both gauge set valves and start the vacuum pump. Allow the vacuum pump to operate for a minimum of 45 minutes after the gauge set low pressure gauge indicates 101 kPa (30 in-Hg). The 45-minute evacuation is necessary to remove any refrigerant from oil left in the A/C evaporator core or A/C condenser core. If the refrigerant is not completely removed from the oil, outgassing will degrade the vacuum and appear as a refrigerant leak.

7. If the low pressure gauge reading will not drop to 101 kPa (30 in-Hg) when the valves on the gauge and manifold set are open and the vacuum pump is operating, close the gauge set valves and observe the low pressure gauge. If the pressure rises rapidly to zero, a large leak is indicated. Recheck the test fitting connections and gauge set connections before installing a new A/C evaporator core or A/C condenser core.

8. After evacuating for 45 minutes, close the gauge set valves and stop the vacuum pump. Observe the low pressure gauge; it should remain at the 101 kPa (30 in-Hg) mark.

� If the low pressure gauge reading rises 34 or more kPa (10 or more in-Hg) of vacuum from the 101 kPa (30 in-Hg) position in 10 minutes, a leak is indicated.

� If a very small leak is suspected, wait 30 minutes and observe the vacuum gauge.

� If a small amount of vacuum is lost, operate the vacuum pump with gauge valves open for an additional 30 minutes to remove any remaining refrigerant from the oil in the A/C evaporator core or A/C condenser core. Then recheck for loss of vacuum.

� If a very small leak is suspected, allow the system to set overnight with vacuum applied and check for vacuum loss.

9. If the A/C evaporator core or A/C condenser core does leak, as verified by the above procedure, install a new A/C evaporator core or A/C condenser core. For additional information, refer to Section 412-03.

A/C Compressor—External Leak Test

1. Install an A/C pressure test adapter on the rear head of the A/C compressor, using the existing manifold retaining bolt.

2. Connect the high and low pressure lines of a manifold gauge set or a refrigerant recovery/recycling station, such as the R-134a A/C Service Center, to the corresponding fittings on the A/C pressure test adapter.

3. Attach the center hose of the manifold gauge set to a refrigerant container standing in an upright position.

4. Hand-rotate the compressor shaft 10 complete revolutions to distribute the oil inside the A/C compressor.

5. Open the low pressure gauge valve, the high pressure gauge valve and the valve on the refrigerant container to allow the refrigerant vapor to flow into the A/C compressor.

6. Using the Refrigerant Leak Detector, check for leaks at the compressor shaft seal and the compressor center seal.

7. If a shaft seal leak is found, install a new shaft seal. For additional information, refer to Section 412-03. If an external leak is found at the center joint of the A/C compressor, install a new A/C compressor.

8. When the leak test is complete, recover the refrigerant from the compressor.



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