SERVICE MANUAL

FOR

90*1, 90*3 & 90*4 SERIES

HEAT PUMPS

TABLE OF CONTENTS

I. Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

II. Unit Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

III. Heat Pump Operation With 9530*715 Standard Ceiling Assemblies . . . . . 8

IV. Wall Thermostat Specifications And Heat Pump Operations With8530-735 Ducted Plenums . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

V. Basic Components And Their Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

VI. The Heat Pump Refrigeration Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

VII. General Electrical Operational Information . . . . . . . . . . . . . . . . . . . . . . . . . 17

VIII. Service Problems And Possible Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

IX. Individual Electrical Component Checkouts . . . . . . . . . . . . . . . . . . . . . . . . 19

X. Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

3

I. WARNINGS

IMPORTANT NOTICE

These instructions are for the use of qualified individualsspecially trained and experienced in installation of this typeequipment and related system components.

Installation and service personnel are required by some statesto be licensed. PERSONS NOT QUALIFIED SHALL NOTSERVICE THIS EQUIPMENT.

WARNING

Improper installation may damage equipment, can create ahazard and will void the warranty.

The use of components not tested in combination with theseunits will void the warranty, may make the equipment inviolation of state codes, may create a hazard and may ruin theequipment.

WARNING - SHOCK HAZARD

To prevent the possibility of severe personal injury orequipment damage due to electrical shock, always be sure theelectrical power to the appliance is disconnected.

CAREFULLY FOLLOW ALL INSTRUCTIONS ANDWARNINGS IN THIS BOOKLET TO AVOID DAMAGETO THE EQUIPMENT, PERSONAL INJURY OR FIRE.

NOTE

The words “Shall” or “Must” indicate arequirement which is essential tosatisfactory and safe product performance.

The words “Should” or “May” indicate arecommendation which is not essentialand not required, but which may be usefulor helpful.

UNIT MODEL NUMBER BREAKDOWN

4

II. UNIT SPECIFICATIONS

90*1 Polar Cub Series Heat Pump

5

90*3 Polar Mach Series Heat Pump

6

90*4 Polar Mach SeriesHeat Pump

7

Roof Top Unit Dimensions

Quick Reference Chart Ceiling Shroud Dimensions

8

III. HEAT PUMP OPERATION WITH 9530*715STANDARD CEILING ASSEMBLIES

If your RV air conditioner is operated from the control panellocated in the ceiling assembly, then there are three controls onthe ceiling assembly that help you control the air conditioner. They are as follows:

A. The Selector Switch – The selector switch determineswhich mode of operation the heat pump will be in. By rotating the selector switch, the operator canobtain any system function desired. System functionsvary depending upon options of both the roof top unitand ceiling assembly. Figures 1 and 2 show selectorswitch location and available functions.

The “Operation” section explains the operationalcharacteristics of each mode of operation.

B. The Thermostat (Temperature Control) – Thethermostat regulates the “ON” and “OFF”temperature setting at which the compressor willoperate (See Figures 1 and 2).

C. Louvers – The louvers are located at both ends of theceiling assembly shroud and are used in directing thedischarge air from the unit.

FIGURE 1

OPERATION

I. For Cooling Operation

A. Turn the selector switch to the “LOW COOL” or“HIGH COOL” position.

B. Rotate the thermostat (temperature control) to theposition that is the most comfortable to you. Thethermostat will turn the compressor on when thetemperature of the air entering the air conditionerrises a few degrees above the setting you haveselected. When the temperature of the air enteringthe air conditioner drops below the selected setting,the thermostat will turn the compressor off. The airconditioner, while in the cooling mode, will continueto cycle the compressor on and off in the abovementioned fashion until the selector switch is turnedto another mode of operation.

C. Position the louvers to the desired direction thedischarge air is to flow.

II. Operation During Cooler Nights (CoolingOperation)

It is important, when the outdoor temperature drops in theevening or during the night to below 75°F, that the thermostat(temperature control) be set at a midpoint between “Warmer”and “Cooler”. If the setting is at “cooler”, the cooler(evaporator) coil may become iced-up and stop cooling. During the day, when the temperatures have risen above 75°F,reset the thermostat switch to the desired setting.

NOTE

Should icing-up occur, it is necessary to let the cooling(evaporator) coil defrost before normal cooling operation isresumed. During this time, operate the unit in the “HIGHFAN” position with the system at maximum air flow. Whenincreased or full air flow is observed, the cooling coil shouldbe clear of ice.

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III. Short Cycling

When an air conditioner is in operation, its compressorcirculates refrigerant under high pressure. Once off, it willtake two to three minutes for this high pressure to equalize.The air conditioning compressor is unable to start against highpressure. Therefore, once the air conditioner is turned off, it isimportant to leave it off for two to three minutes beforerestarting.

Short cycling the compressor (or starting it before pressureshave equalized), will in some instances, kick the circuitbreaker or overload.

IV. For Heating Operation

A. Turn the selector switch to the “HIGH HEAT”position. At “HIGH HEAT”, the fan operates on highspeed with heat output at maximum.

B. Rotate the thermostat (temperature control) switch tothe position that is the most comfortable to you. Thethermostat will turn the compressor/heater on whenthe temperature of the air entering the unit dropsbelow this setting a few degrees, and automaticallyturns off when the temperature of the air entering theunit rises a few degrees above this setting. Thecompressor/heater will continue to cycle on and off inthis fashion until the selector switch is turned toanother mode of operation.

C. Position the louvers to the desired direction thedischarge air is to flow.

Discharge air temperature can be controlled to someextent by opening or closing the louvers.

When the louvers are closed, the warmest localizeddischarge air is achieved. Fully opened louvers willthrow the warm discharge air to the back and front of

the vehicle for more efficient circulation and fasterwarm-up. Although the air temperature is lower withthe louvers fully opened, the heating capacity is stillthe same.

NOTE

The heat pump will operate on reverserefrigerant cycle while heating at outdoortemperatures above approximately 40 degrees F. When the outdoor temperature is belowapproximately 40 degrees F, theheat pump compressor will shut down toprevent outdoor coil freeze-up. At this time, the auxiliary electric resistanceheater will be utilized to take the chill outof the indoor air. The electric resistanceheater is not a substitute for a furnace atthese low outdoor temperatures.

V. For Air Circulation Only

A. Turn the selector switch to “LOW FAN” or formaximum air flow, to “HIGH FAN”.

D. Position the louvers to the desired direction thedischarge air is to flow.

NOTE

When the selector switch is in “LOWFAN” or “HIGH FAN” position, theblower motor will operate continuously.

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IV. WALL THERMOSTAT SPECIFICATIONS ANDHEAT PUMP OPERATIONS WITH

DUCTED PLENUMS

For 8530*345* & 8530*346*1 Stage Heat Pump

OPERATION

The display indicates room temperature and the word ROOMis shown on the LCD until the temperature selector is pressed;at which time the display temporarily indicates the setpointtemperature and the word SET is shown on the LCD. Eachtime the UP arrow is pressed, the setpoint will increase. Eachtime the DOWN arrow is pressed, the setpoint will decrease. Once the termperature selector button is no longer pressed fora few seconds, the room temperature will again be displayed,and the word ROOM will be displayed on the LCD.

In electric heat mode, if the heat pump is unable to satisfy thethermostat, the heat pump goes into lockout. See heat pumpand back-up heat example on Page 4 for conditions of heatpump lockout. DIFF will display on the thermostat LCDindicating backup heating is required to satisfy the thermostat.

In gas heat mode, the gas furnace will provide the only sourceof heat and the heat pump is locked out.

Note 1

The temperature is displayed in degrees Fahrenheit as a factoryset default (See Figure 2). To display in degrees Celsius,move the jumper marked “F” and “C” to bridge betweenmiddle pin and position “C”, then cycle 12 volt power off thenback on again.

Refer to operation table (pages 11 &12) for a moredetailed listing of operation sequence.

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OPERATION CHART

The chart below shows the system functions with the 8430*345* and 8530*346* thermostats.After the entire air conditioning system (and furnace system) is installed, check each position function.

8530*345* And 8530*346*

1-STAGE HEAT PUMP THERMOSTAT OPERATION TABLE

Mode Switch

Fan ModeSwitch

Fan Speed Switch

Calling Operation

1 Cool Auto Lo No No functions occur in this mode

2 Cool Auto Lo Yes GL-FAN Low (Gray), Y-Compressor(Yellow) energized

3 Cool On Lo No GL-FAN Low (Gray), energized

4 Cool On Lo Yes GL-FAN Low (Gray), Y-Compressor(Yellow) energized

5 Cool Auto Hi No No functions occur in this mode

6 Cool Auto Hi Yes GH-FAN High (Green), Y-Compressor(Yellow) energized

7 Cool On Hi No GH-FAN High (Green), energized

8 Cool On Hi Yes GH-FAN High (Green), Y-Compressor(Yellow) energized

9 Off Auto Low or Hi No No functions occur in this mode

10 Off On Lo No GL-FAN Low (Gray), energized

11 Off On Hi No GH-FAN High (Green), energized

12 Gas Heat Auto or On Lo or Hi No No functions occur in this mode

13 Gas Heat Auto or On Lo or Hi Yes WF-Furnace (White) energized to run the furnace

14 Elec Heat Auto or On Lo or Hi No No functions occur in this mode

15 Elec Heat Auto or On Lo or Hi Yes WHP-Heat Pump (White/Black) will beenergized to run the heat pump

16 Elec Heat Auto or On Lo or Hi Back-up Heat5 Degrees

below setpoint

WHP-Heat Pump (White/Black) will beenergized to run the heat pump and WF-Furnace (White) will be energized

to run the furnace.

There is a 3 minute anti-short cycle delay timer built into the thermostat.

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Note 2

Heat Pump And Back-up Heat Example To Call For Gas Furnace

Setpoint Indoor Temperature Operation

70 70+ No functions occur.69 Heat Pump turns on (Primary heat source)71 Heat Pump turns off (Thermostat satisfied)69 Heat Pump turns on65 Gas Furnace turns on (Heat Pump not able to satisfy

Thermostat) (First strike for backup heat counter)71 Gas Furnace turns off, heat pump turns off (Thermostat

satisfied)69 Heat Pump turns on65 Gas Furnace turns on (Heat Pump is again unable to satisfy

Thermostat), (backup heat counter reaches 3rd strike andHeat Pump is locked out for 1 hour + 45 minutes).Backup heat counter is reset if Heat Pump is running for more than 20 minutes and does not call for backupheat.

71 Gas Furnace turns off (Thermostat satisfied).69 Gas Furnace turns on (Becomes Primary heat source).71 Gas Furnace turns off (Thermostat Satisfied)

After 1 hour + 45 minutes lockout69 Heat Pump turns on (Resumes as Primary heat source).65 Gas Furnace turns on, heat pump turns off (Becomes

Primary heat source) (Heat Pump is locked out for another1 hour + 45 minutes).

71 Gas Furnace turns off (Thermostat satisfied).After 1 hour + 45 minutes lockout

69 Heat Pump turns on (Resumes as Primary heat source).71 Heat Pump turns off (Thermostat satisfied).

(backup heat counter is reset any time Heat Pumpsatisfies thermostat setpoint and does not need GasFurnace).

The word “DIFF” will display on LCD when backup heat is operating.

13

FIGURE 2

14

V. BASIC COMPONENTS AND THEIR FUNCTIONSHEAT PUMP REFRIGERATION

SYSTEM DIAGRAM

15

I. Indoor Coil (Cooling Mode)

The purpose of the finned evaporator coil is to transfer the heatfrom the warm and moist indoor air to the cold low pressurerefrigerant.

As the heat leaves the air, the air temperature drops and someof the moisture in the air condenses from a vapor to a liquid. The liquid water (condensate) is drained onto the roof of therecreational vehicle. As the heat enters the refrigerant in theevaporator, it causes the refrigerant to evaporate (change froma liquid to a vapor).

The refrigerant remains at nearly constant temperature (calledevaporator temperature or low side saturation temperature) inthe evaporator since there are both liquid and vapor together. However, near the outlet of the evaporator coil, all of theliquid has boiled (evaporated) away and from there on, thetemperature of the vapor rises (the vapor becomessuperheated). It is necessary that the vapor becomesuperheated because it is headed down the suction line to thecompressor, and the compressor can only pump superheatedvapor. Any vapor (which might be present if the vapor werenot superheated) could cause serious mechanical damage tothe compressor.

2. Suction Line

The suction line is the copper tube which carries thesuperheated vapor refrigerant from the evaporator to thecompressor.

3. Compressor

The compressor is called a hermetic compressor which meansit is completed sealed (welded together). It is, therefore, notinternally field serviceable. Inside the compressor housing isbasically:

a) an electric motor which drives the compressor,

b) a pump which is designed to pump superheatedvapor,

c) a supply of special refrigerant oil. A small portion ofthe oil will circulate out through the system with therefrigerant, but will constantly return to thecompressor with the refrigerant, so the compressorwill not run out of oil.

4. Outdoor Coil (Cooling Mode)

The purpose of the finned condenser coil is to transfer heatfrom the high pressure refrigerant to the warm outdoor air. Asthe outdoor air passes over the coil, the heat transfer will cause the air temperature to rise. Thus the condenserdischarge air will be several degrees warmer than thecondenser entering air.

As the refrigerant passes through the first few tubes of thecondenser, its temperature will be lowered or it will be de-superheated. After the refrigerant is de-superheated, it willbegin to condense or change from a vapor to a liquid and willremain at a nearly constant temperature throughout almost allof the remainder of the coil. This temperature is called thecondensing temperature or high side saturation temperatureand will always be higher than the condenser entering airtemperature.

Near the bottom of the condenser, the refrigerant will all becondensed to a liquid and from there on, its temperature willdrop to more nearly the temperature of the outdoor air. Afterthe temperature of the refrigerant drops below condensing orsaturation temperature, we call its condition sub-cooled liquid.

During all of the three processes in the condenser (de-superheating, condensing, sub-cooling), the refrigerant givesup heat; but most of the heat is given up during the condensingprocess.

5. Reversing Valve

The reversing valves main function is to reverse the flow ofrefrigerant. Internally, it is composed of two pistons on asliding block or cylinder with two openings. The operation ofthe piston block is controlled by a solenoid valve. Thesolenoid valve controls the flow of the refrigerant, whichproduces a pressure difference in the valve itself. When thesolenoid valve is energized, it is in the heating mode. When itis de-energized, it is in the cooling mode.

6. Discharge Line

The discharge line carries the refrigerant out of the compressorand to the reversing valve. The reversing valve thendistributes this refrigerant to the outdoor coil during thecooling mode, and to the indoor coil in the heating mode. Remember that as the refrigerant entered the compressor, itwas superheated vapor. As the compressor works on therefrigerant, it adds more heat and also compresses therefrigerant into a smaller space. The refrigerant, therefore,leaves the compressor highly superheated - so if the dischargeline is hot to the touch (burns), don’t be surprised - it shouldbe.

7. By-Flow Restrictor

The by-flow restrictor is the metering device for the heatpump. The restrictor is made up of two orifices positionedback to back. There is a space between the orifices. As thesystem is either in the cooling or heating mode, it forces one ofthe orifices to seat at one of the tapered ends and force theother to break its seal. Refrigerant goes around one orifice andthrough the other, establishing the pressure drop. The orificesare different sizes to accommodate for the difference in thecondenser and evaporator sizes.

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8. High and Low Sides

It is customary for air conditioning technicians to use the termshigh side and low side. In doing so, we refer to the parts of therefrigerant circuit which, when the system is running, containshigh pressure (high side) and low pressure (low side). Thehigh side of the system exists from the discharge port of thecompressor to the metering device. The low side is from themetering device to the compressor cylinders. The dividingpoints then are the metering device and the compressorcylinders.

The high side pressure is also referred to as heat pressure orcondensing pressure, and the low side pressure is also referredto as suction pressure or evaporator pressure.

It is impossible to state the exact pressures that will exist in thehigh side or low side because those pressures will both varywith different temperature and humidity conditions both insideand outside the recreational vehicle.

9. Refrigerant Charge

The system covered by this service manual all use a refrigerantcalled monochlorodifluoromethane (better known as R-22).

We know that R-22 is not a deadly gas because many of ushave breathed it several times and are still living. But, no onehas said that R-22 is completely safe to breathe. A wiseservice technician will always keep a work space wellventilated if R-22 can escape into the air. IF R-22 IS

RAISED TO A HIGH TEMPERATURE IN THE PRESENCEOF WATER (WHICH ALWAYS EXISTS IN THEATMOSPHERE), IT DEFINITELY DOES BECOME ATOXIC GAS by changing from virtually harmless R-22 tophosgene and hydrofluoric acids. So, if R-22 in the air isexposed to a welding or soldering torch flame, burning waterheater burner, burning furnace burner, etc., be sure to avoidbreathing it.

The temperature at which R-22 changes to toxic gases andacids varies with the amount or concentration of water present,i.e. the greater the concentration of water, the lower thetemperature and vise versa. High temperatures normally existinside a refrigerant circuit, so we must keep the circuit asabsolutely dry as possible to prevent the formation ofdestructive acids.

Liquid R-22 in the atmosphere will always be about -41degrees. Therefore, always wear safety glasses when workingwith R-22.

Again, unburned R-22 is not a deadly gas. By usingreasonable safety precautions, the service technician will notbe hurt.

In addition to being almost non-toxic, R-22 is non-flammable,non-corrosive and miscible (mixable) with oil. It also has ahigh latent heat value. This means that it must absorb a largeamount of heat per pound to vaporize or change from a liquidto a vapor, and it must give up a large amount of heat perpound to condense or change from a vapor to a liquid.

VI. THE HEAT PUMP REFRIGERATION CYCLE

The Heat Pump is a refrigeration system like any otherrefrigeration system, that heat transfers from one place toanother by the change in state of a liquid. The Heat Pump canreverse the action or direction of heat transfers. For summercooling, it can remove heat from occupied areas and dispose ofthe heat into outside air. For any time heat is needed, itreverses the action with a reversing valve and will

also remove heat from the outside air source and supply heat tothe occupied area. We re-label the coils as indoor and outdooras they are now dual purpose, depending on the usage desired. The outdoor coil is the condenser in the cooling cycle and theevaporator in the heating cycle. The indoor coil is theevaporator coil in the cooling cycle and the condenser coil inthe heating cycle.

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VII. GENERAL ELECTRICAL OPERATIONALINFORMATION

HEAT PUMP ELECTRICAL OPERATION9530*715 STANDARD CEILING ASSEMBLIES

All air conditioning functions operate the same as a standardair conditioner. While in the heating mode with the selectorswitch in the High Heat position, the #3 terminal will energizethe reversing valve and the compressor. At the same time, the#1 terminal will energize high speed on the fan motor. Therefrigeration cooling cycle is now reversed and the airconditioner is now heating running on high speed fan.

The freeze switch or outdoor thermostat located on thecondenser coil opens at 18° (± 6°) actual coil temperature, notambient temperature. When this switch opens, the compressorshuts off. The reversing valve remains in the heating positionand the fan continues to run on high speed. When thecompressor shuts off, the freeze switch will also energize a5600 BTU electric heating element.

This heating element will continue to run until the freezeswitch resets allowing the operation of the heat pump. At notime will you have the heat pump and the electric heat strip onat the same time.

NOTE

The heat pump should be considereda cooling unit which also providesheat at outdoor temperatures abovefreezing. This unit will shut down atlow ambient conditions that wouldcause outdoor coil freeze-up, approximately 40 degrees.

HEAT PUMP ELECTRICAL OPERATION WITHDUCTED CEILING ASSEMBLIES

All air conditioning functions operate the same as a standardair conditioner. While in the heating mode with the wallthermostat in the electric heating position, the white wire (orthe “W” terminal) will energize the reversing valve relay in theceiling assembly. At the same time, it will energize both thecompressor relay terminal “Y” and high speed fan relayterminal “GH” through blocking diodes on the terminal board. Hence, the refrigeration cooling cycle is now reversed and theair conditioner is now heating and running on high speed fan.

The blocking diode located on the terminal board just ahead ofthe “Y” terminal prevents 12 VDC (+) feedback to the coolingfan circuit while in the heating mode. Without this, someonecould put the fan switch on the thermostat in the low position,and energize both high and low speed fan operations at thesame time.

The freeze switch or outdoor thermostat located on thecondenser coil opens at 18 degrees (± 6°) actual coiltemperature, not ambient temperature. When this switch opensthe compressor shuts off. The reversing valve remains in theheating position and the fan continues to run on high speed aslong as the wall thermostat is still calling for electric heat. When the compressor shuts off, the freeze switch will alsoenergize a 5600 BTU electric heating element.

This heating element will continue to run until the wallthermostat is satisfied or until the freeze switch resets allowingthe operation of the heat pump. At no time will you have theheat pump and the electric heat strip on at the same time.

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VIII. SERVICE PROBLEMS AND POSSIBLE SOLUTIONS

SERVICE PROBLEMS WITH THE HEAT PUMP AND THEDUCTED CEILING ASSEMBLY AND WALL THERMOSTAT

The following list of service problems covers only some of themore common problems which may occur and lists only themore probable causes.

In many instances, it will be necessary to use the wiringdiagram in this guide to checkout the electrical circuits step bystep, starting at the power source.

19

SERVICE PROBLEMS WITH THE HEAT PUMPSTANDARD CEILING ASSEMBLIES

The following list of service problems covers only some of themore common problems which may occur and lists only themore probable causes.

In many instances, it will be necessary to use the wiringdiagram in this guide to check out the electrical circuits step bystep, starting at the power source.

IX. INDIVIDUAL ELECTRICAL COMPONENTCHECKOUTS

THINK SAFETY

1. Power Supply - From Commercial Utility

1) Wire Size

The power supply to the air conditioner must come through acircuit breaker or time delay fuse. The power supply must be20 amperes and 12 AWG wire minimum. Any size larger wireat any time may be used and should be used if the length ofthe wire is over 32 feet.

2) Color Code

The electric power from the electric service panel should bedelivered through a 3 conductor cable and the ServiceTechnician should check to be sure the color code is correct. The electrician probably installed the cable with the colorsaccording to code, but don’t bet your life on it.

b) The wire with black insulation is the hotwire and there should be 115 volts (domesticUSA) between it and either of the otherwires. All switches, fuses, circuit breakers,disconnects, etc. should be in this line.

20

b) The wire with the white insulation is theneutral. There should be 115 volts(domestic USA) between the neutral and thehot (black) wire, but there should be 0 voltsbetween the neutral and the ground (thegreen wire or the frame of the airconditioner). There must be no switches,fuses, disconnects, etc. of any kind in theneutral wire.

c) The third wire may be covered with greeninsulation or it may be a bare metal wire. Itis the ground wire. There must be 115 volts(domestic USA) between this wire and thehot (black) wire and 0 volts between it andthe neutral (white) wire. The ground wiremust be securely fastened to the airconditioner cabinet. A green headed screwis provided for this purpose.

3) Voltage

The voltage (electrical pressure) at the unit should be 115 volts(domestic USA) and all electrical components will performbest at the correct voltage. However, the voltage will vary andthe air conditioning system will perform satisfactorily withinplus or minus 10% of the rated (115) voltage (domestic USA). Therefore, the voltage has to be between 103.5 volts and 126.5volts.

2. Power Supply - Generated By On-Board MotorGenerator

If the power supply for the recreational vehicle is supplied byan on-board motor generator, its wiring may be identical to thecommercial power described above.

There are, however, some motor generators on which both thecurrent carrying leads are insulated from the ground. That isto say, there is no grounded neutral, so there will be 115 volts(domestic USA) between the black and white leads, but therewill be 0 volts between either lead and ground.

WARNING: The service technician must keep in mind whenchecking to make sure that the power is turned off. Checkonly between the hot (black) lead and the neutral (white) lead. The black lead could still be hot even though there is 0 voltsbetween it and ground.

3. Compressor Motor

The compressor motor is located inside the hermeticcompressor housing and is therefore, not accessible for serviceor visual observation in the field. However, the motor windingcondition can be analyzed by using an ohm meter. Be sure toremove all the leads from the compressor terminals beforemaking this check.

a) If the resistance between any two terminals is 0 ohms,the motor windings are shorted.

b) If the resistance between any terminal and thecompressor housing is anything but infinity, thewinding is grounded.

4. Overload Switch

Mounted internally within the compressor housing is anoverload switch. The switch is connected in series with thecommon terminal; so if the switch opens, it will cut the powerto the compressor motor. The switch will open as the result ofeither or both of two conditions that could be harmful to thecompressor.

a) High Amperes (Current)

The switch contains a heater which increases intemperature as the current increases. The highertemperature warps the switch and will cause it toopen before the windings reach a dangeroustemperature.

b) High Temperature (Thermal)

The switch is clamped tightly against the compressorhousing and located close to the windings. Therefore,as the windings reach a higher temperature, it takesless current to cause the switch to open.

As can be seen, the switch is always affected by a combinationof current to the compressor and winding temperature.

5. Fan Motor

The air conditioning unit has one double end shaft fan motor. On one shaft end is mounted a centrifugal or squirrel cageblower which draws air (return air) out of the recreationalvehicle and blows the conditioned air down into therecreational vehicle. On the other shaft end is mounted anaxial flow or propeller type fan which circulates outdoor airthrough the condenser coil.

An important step in installing a replacement fan motor is tocheck the direction of rotation before it is installed. On allmodels, the condenser fan pulls the air through the coil.

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Fan Motor Check Procedure

If a fan motor refuses to perform properly, it can be checked inthe following manner:

1. Be sure the motor leads are connected to the properpoints –

a) The black wire from the motor connects to ablack wire inside a wire nut then the blackwire connects through the disconnect plug tothe selector switch. The red wire from themotor connects to a red wire in a wire nut,then the red wire connects through thedisconnect plug to the selector switch.

b) The white wire from the motor connects to awhite wire in a wire nut then the white wireconnects through the disconnect plug to thethermostat.

c) The brown wires from the motor connect tothe fan capacitor.

2. To check the motor winding resistance carefully,check the resistance between each of the wires andground (preferably a copper refrigerant tube for agood connection). These readings must be infinity. Any continuity means the windings are grounded.

If there is a reading of 0 between any two leads, themotor is shorted and is no good. If there is a readingof infinity between any two leads, the winding is openand the motor is no good.

6. Selector Switch - Free Delivery Ceiling Assemblies

The selector switch is mounted on the left side of the interiorceiling assembly. Check for continuity between the terminalswith an ohm meter.

Switch Position Continuity

HEAT L - 1 - 3LO FAN L - 1HI FAN L - 2LO COOL L - 1 - 4HI COOL L - 2 - 4

7. Thermostat (Mechanical Rotary)

The thermostat (temperature controller) is mounted on theright side of the interior ceiling assembly. The thermostatcontrols the on-off cycle of the compressor when the selectorswitch is in the cooling position and the on-off cycle of theheat pump or electric heater when the selector switch is in the

heating position. The thermostat is actuated by sensing thetemperature of the return air through the vent where the bulb islocated. Check continuity between terminals with an ohmmeter.

8. Heating Element

The heating element is a resistance heater of 1600 watts (5600BTUH) capacity and is connected across the line when theselector is set for heating and the thermostat is calling for heat. The current draw of the heater (element only) will be 13.9amperes at 120 volts (domestic USA models).

9. Limit Switch (Heating Element)

The limit switch is a safety switch and is mounted in theheating element frame. It will open and break the circuit ontemperature rise in case the air flow through the heaterbecomes low enough to cause the heater to overheat. Limitswitch may be checked for continuity with an ohm meter.

10. Run Capacitors

The purpose of the run capacitors is to give the motors startingtorque and to maintain high power factor during running. Therun capacitors are always connected between the start and runor main terminals of the motor.

One of the terminals of the run capacitors will have a red dot(the identified terminal). The identified terminal shouldalways be connected to the run or main terminal of the motorand to the neutral line.

Capacitor Check

There are several capacitor test devices available. The ohmmeter is one of them. The ohm meter cannot verify acapacitors MFD (microfarrad) value. However, the followingprocedures will show you how to use an ohm meter todetermine if the capacitor is good, open, shorted or grounded.

Before testing any capacitor, always perform the followingprocedure:

a) Disconnect all electrical power to the air conditioner.

b) Discharge the capacitor with a 20,000 ohm (approx. 3watt) resistor or larger.

c) You may discharge capacitors with a standard voltmeter if you use a scale over 500 volts and touch theleads (one lead to each side of the capacitor), the voltmeter will discharge the capacitor.

d) Identify and disconnect the wiring from the capacitor.

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CAPACITOR

OHM METER

HIGH LOW

OK

Indicator sweeps back and forthas shown above. Capacitor is good.

HIGH LOWOPEN

e) Set and zero the ohm meter on the “highest” scale.

When testing for a good, open or shorted capacitor,perform the following checks: Place the ohm meterleads across the capacitor terminals (one lead on eachterminal) and perform a continuity test. Then observethe action of the meter needle or indicator. Reversethe leads and test again. The result should be thesame. Note: If the capacitor had not been properlydischarged, a false reading could be indicated on thefirst test. Always test several times (reversing theleads with each test). This will verify the capacitorscondition.

Good Capacitor

If the capacitor is good, the indicator will move from infinity(the left side), up towards zero ohms and slowly return back toinfinity. Reverse the leads and test again. The result shouldbe the same.

Open Capacitor

If the capacitor is open, the indicator will show no deflectionor movement. Reverse the leads and test again. If there is noindicator movement on the second test, the capacitor is open. Open capacitors are defective and must be replaced.

Shorted Capacitor

If the capacitor is shorted, the indicator will move toward andsometimes hit zero ohms, and will stay there. This indicates acompleted circuit through the inside of the capacitor (shorted). Shorted capacitors are defective and must be replaced.

Grounded Capacitor

When testing for a grounded capacitor, perform a continuitycheck between each terminal on the capacitor and the baremetal of the capacitors case. Any indication of a circuit(constant resistance) from either terminal to case, indicates agrounded capacitor. Grounded capacitors are defective andmust be replaced.

Indicator shows no movement. Needle staysto the left side. If needle shows no movement after

reversing the leads, the capacitor is open.

HIGH LOWSHORT

Indicator moves to the right side of thescale and stays there (indicating a completed

circuit). The capacitor is shorted.

Indicator moves to the right side of the scaleand stays there (indicating a completed

circuit). The capacitor is grounded.

OHM METER

CAPACITOR

HIGH LOWGROUNDED

23

11. Start Capacitor

Most models use a start capacitor and a start relay to give thecompressor high starting torque. The compressor will,therefore, start against normal pressure difference (headpressure minus suction pressure) even when shut down for ashort period of time. The start relay will disconnect the startcapacitor when the motor reaches approximately 75% runningspeed.

12. Start (Potential) Relay

The start relay consists of –

a) Normally closed contacts internally betweenterminals #1 and #2 which switch in the startcapacitor in parallel to the run capacitor during shutdown and then switch out the start capacitor when themotor reaches approximately 75% normal runningspeed.

b) A high voltage coil internally between terminals #5and #2 to actuate the contacts. The coil is too weakon line voltage to actuate the contacts, but it isconnected in series with the start winding and it getsthe generated voltage of the start winding portion ofthe compressor motor. This generated voltage ismuch higher than line voltage and varies with the

speed of the motor. Therefore, since the relay isdesigned to open the contacts at 75% of normalrunning voltage (measured between terminals #5 and#2), the contacts will open (thus disconnect the startcapacitor) at approximately 75% of normal runningspeed.

13. Thermistor

The thermistor is a freeze protection device installed in thecompressor relay circuit to prevent evaporator coil freeze-ups. This device is a semi-conductor which has electrical resistancethat varies with temperature. The thermistor cutouttemperature is 26 degrees F (± 3°) and reset temperature is 40 degrees F (± 3°).

14. Outdoor Thermostat (Freeze Switch)

The outdoor thermostat is a normally closed switch wired inseries with the compressor common wire.

The outdoor thermostat is located on the condenser coil opensat 18 degrees (± 6°) actual coil temperature, not ambienttemperature. When this switch opens, the compressor shutsoff.

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15. Printed Circuit Boards (Low Voltage Controls)Ducted Ceiling Plenums

The printed circuit boards and low voltage control circuits forinducted ceiling plenum applications simply replace theselector switch and rotary thermostat controls on the manuallycontrolled units. The printed circuit boards purpose is toreceive the various (12 VDC) low voltage control signals fromthe wall thermostat, and then use these signals to close therelay contacts located on the printed circuit board. Once therelay has closed, the high voltage power goes through the heatpump conduit assembly to operate the compressor, reversingvalve coil or the fan motor.

Troubleshooting Tips

1) To troubleshoot this printed circuit board, it will firstbe necessary to verify the presence of low voltage (12VDC) to the low voltage terminal board connections(see the chart below). For wiring schematic, seediagram on page 21.

B -12 VDC for all relay coilsY +12 VDC for compressor relay coilGH +12 VDC for hi fan relay coilGL +12 VDC for low fan relay coilW +12 VDC for heat relay coilF- - - - - Coil sensor opens circuit to compressor

F- - - - - relay. In case of coil freeze-up, the switchopens 26 degrees F. and closes 40 degrees F. It is permissible to jumper these twoterminals for test purposes only.

Example:

For high speed fan operation, a 12 VDC potentialbetween the terminals GH (+) and B (-) are necessary. For compressor operation, a 12 VDC potentialbetween Y (+) and B (-) is necessary. If this is notpresent, see the wall thermostat checkout procedure. The problem is evidently not in the printed circuitboard.

2) After the low voltage control circuits have beenverified, we may now check to see if the relays on theprinted circuit board are operating. The first step isto insure there is a 115 VAC power supply to theprinted circuit board high voltage terminals. Secondly, locate the 9 pin high voltage connectorplug located on top of the wiring box (see the wiringdiagram on page 23 of this manual). This is anexcellent place for measuring high voltage outputfrom the printed circuit board to the upper unitcomponents. It will be necessary to unplug the upperunit to perform these tests. The chart below indicateswhich pin terminals will have a 115 VAC potentialbetween them if the relays do successfully close.

25

X. WIRING DIAGRAM90XX Polar Cub, Polar Mach Heat Pumps

120 VAC

26

WIRING DIAGRAM FOR THE7530-736 AND 8530-735 DUCTED

CEILING ASSEMBLIES

27

WIRING DIAGRAM FOR9530x715 FREE DELIVERY HEAT PUMP

CEILING ASSEMBLY 120 VAC

28

WIRING DIAGRAM FOR8530X633, 8530X73X9530X751, 9530X755

HEAT PUMP CEILING ASSEMBLIES120 VAC/12 VDC

29

WIRING DIAGRAM FOR 8530B751 HEAT PUMP ZONE CONTROL KIT

120 VAC

RV ProductsA Division of Airxcel, Inc.

P.O. Box 4020Wichita, KS 67204

1976-470 (1-07)