Carrier Heat Pump Troubleshooting

The tables below contain the lists of possible breakdowns which may happen with Carrier heat pumps of different modifications. In case of Carrier heat pump not working you should address these checklists. Here you can find the failures of modifications like AQUAZONE, COMFORT, Infinity, Deluxe, and others.
There are types of faults and problems with detailed descriptions, possible causes and solutions which may be recommended in the certain situations. If you feel the temperature in your house is getting higher, it may be because of heat pump fan not spinning, and therefore, heat pump not cooling. The information given below can be helpful for you then.

Carrier AQUAZONE 50HQL072-120 Heat Pump Troubleshooting

CHECKPOSSIBLE CAUSESOLUTION
Is fault LED Blinking 1 time?High Pressure fault - no or low water flowCheck water valves and/or pumps for proper operation. Check for water coil blockage.
High Pressure fault - high water temperatureCheck water temperature - is it in range?
High Pressure fault - fouled or scaled water coilCheck for proper flow rate and water temperature, but low water side temp rise in cooling.
Check fan motor for proper operation.
Is fault LED Blinking 2 times?High Pressure fault - no or low airflowCheck air filter.
Inspect air coil for dirt/debris.
Check ductwork - are dampers closed or blocked?
Low Pressure fault - no or low airflowCheck fan motor for proper operation.
Check air filter
Inspect air coil for dirt/debris
Check ductwork - are dampers closed or blocked?
Low Pressure fault - low refrigerantCheck refrigerant pressure with gage set
Is fault LED Blinking 3 times?Low Pressure fault - no or low water flowCheck water valves and/or pumps for proper operation. Check for water coil blockage.
Low Pressure fault - low refrigerantCheck for proper flow rate and water temperature, but low water side temp drop in heating.
Freeze fault, water coil - no or low water flowCheck water valves and/or pumps for proper operation. Check for water coil blockage.
Freeze fault - low water temperatureCheck water temperature - is it below 40 F entering? If heat pump is connected to a closed loop with anti- freeze check that the "FREEZE 1 * resistor on the Complete C board has been cut to set the unit to anti- freeze mode.
Freeze fault - low refrigerantCheck refrigerant pressure with gage set
Blinking 4 times?Condensate fault - poor drain- ageCheck condensate pan for high water level. Check drain line for blockages, double trapping or inadequate trapping.
Condensate fault - blocked return airCheck condensate pan for high water level. Check air filter and return air ductwork tor blockage. Check that there is adequate space between the return air opening and walls or other obstructions on free return applications.
Is fault LED Blinking 5 times?Brown out fault - low supply voltageCheck primary voltage - ensure it is within the limits listed on the unit data plate.
Brown out fault - overloaded control circuitCheck control voltage - if it is below 18 V check accessories connected to the unit and insure that they do not exceed the VA draw
Brown out fault - bad thermostat connectionCheck that thermostat wiring is proper gage and length, that it is not damaged and that all connections at the thermostat and heat pump are secure.
Is fault LED Blinking 6 times?Freeze fault, air coil - no or low airflowCheck fan motor for proper operation.
Check air filter
Inspect air coil for dirt/debris
Check ductwork - are dampers closed or blocked?
Freeze fault, air coil - blocked return airCheck that there is adequate space between the return air opening and walls or other obstructions on free return applications.
Freeze fault, air coil - low refrigerantCheck refrigerant pressure with gage set.

Carrier COMFORT 25HCC5018 Heat Pump Troubleshooting

CHECKPOSSIBLE CAUSESOLUTION
Is fault LED Blinking 1 time?High Pressure fault - no or low water flowCheck water valves and/or pumps for proper operation. Check for water coil blockage.
High Pressure fault - high water temperatureCheck water temperature - is it in range?
High Pressure fault - fouled or scaled water coilCheck for proper flow rate and water temperature, but low water side temp rise in cooling.
Check fan motor for proper operation.
Is fault LED Blinking 2 times?High Pressure fault - no or low airflowCheck air filter.
Inspect air coil for dirt/debris.
Check ductwork - are dampers closed or blocked?
Low Pressure fault - no or low airflowCheck fan motor for proper operation.
Check air filter
Inspect air coil for dirt/debris
Check ductwork - are dampers closed or blocked?
Low Pressure fault - low refrigerantCheck refrigerant pressure with gage set
Is fault LED Blinking 3 times?Low Pressure fault - no or low water flowCheck water valves and/or pumps for proper operation. Check for water coil blockage.
Low Pressure fault - low refrigerantCheck for proper flow rate and water temperature, but low water side temp drop in heating.
Freeze fault, water coil - no or low water flowCheck water valves and/or pumps for proper operation. Check for water coil blockage.
Freeze fault - low water temperatureCheck water temperature - is it below 40 F entering? If heat pump is connected to a closed loop with anti- freeze check that the "FREEZE 1 * resistor on the Complete C board has been cut to set the unit to anti- freeze mode.
Freeze fault - low refrigerantCheck refrigerant pressure with gage set
Blinking 4 times?Condensate fault - poor drain- ageCheck condensate pan for high water level. Check drain line for blockages, double trapping or inadequate trapping.
Condensate fault - blocked return airCheck condensate pan for high water level. Check air filter and return air ductwork tor blockage. Check that there is adequate space between the return air opening and walls or other obstructions on free return applications.
Is fault LED Blinking 5 times?Brown out fault - low supply voltageCheck primary voltage - ensure it is within the limits listed on the unit data plate.
Brown out fault - overloaded control circuitCheck control voltage - if it is below 18 V check accessories connected to the unit and insure that they do not exceed the VA draw
Brown out fault - bad thermostat connectionCheck that thermostat wiring is proper gage and length, that it is not damaged and that all connections at the thermostat and heat pump are secure.
Is fault LED Blinking 6 times?Freeze fault, air coil - no or low airflowCheck fan motor for proper operation.
Check air filter
Inspect air coil for dirt/debris
Check ductwork - are dampers closed or blocked?
Freeze fault, air coil - blocked return airCheck that there is adequate space between the return air opening and walls or other obstructions on free return applications.
Freeze fault, air coil - low refrigerantCheck refrigerant pressure with gage set.

Carrier Infinity 25VNA036 Heat Pump Troubleshooting

FAULTDESCRIPTIONSOLUTION
Motor rocks slightly when startingThis is normal start-up for ECM.
Motor will not startNo movementCheck power at motor.
Check low voltage (24-vac R to C) at motor.
Check low voltage connections (G.Y W. R. C) at motor.
Check for unseated Dins in connectors on motor harness.
Check motor for tight shaft.
Perform motor/control replacement check.
Run moisture check.
Motor rocksCheck for loose or non-compliant motor mount.
Make sure blower wheel is tight on shaft.
Perform motor/control replacement check.
Motor oscillates up and down while being tested off of blowerIt is normal for motor to oscillate with no load on shaft.
Motor starts, but runs erraticallyVaries up and down or intermittentCheck line voltage for variation or “saq."
Check law voltage connections (G,Y W, R ; C) at motor, unseated pins in motor harness connectors.
Check “Bk” for erratic cfm command (in variable speed applications).
Check system controls, thermostat.
Perform moisture check.
“Hunts" or “puffs” at high cfm (SDeed)If removing panel or filter reduces “puffing,” reduce restriction or reduce maximum airflow.
Stays at low cfm despite system call for cool or heat cfmCheck lew voltage (thermostat) wires and connections.
Verity fan is not in delay mode. Wait until delay is complete.
Perform motor/control replacement check.
Verify fan is not in delay mode. Wait until delay is complete.
Perform motor/control replacement check.
Excessive noiseNoisy blower or cabinetdetermine if it’s air. cabinet, duct, or motor noise.
Check for loose blower housing. panels. etc.
If high static is creating high blower speed, check for air whistling through seams in ducts, cabinets, or panels.
If high static is creating high blower speed. check for cabinet/duct deformation.
“Hunts" or “puffs” at high cfm (speed)If removing panel or filter reduces '‘puffing; reduce restriction or reduce maximum airflow.
Evidence of moistureMotor failure or malfunction has occurred and moisture is presentReplace motor and perform moisture check..
Evidence of moisture present inside air moverPerform moisture check.

Carrier Deluxe 38YZA Heat Pump Troubleshooting

MalfunctionsCauseWhat should be done?
Unit does not startPower cutWait for power to be restored.
Unit may have become unplugged.Check that the plug is securely in the wall receptacle.
Fuse may have blown.Replace the fuse.
Battery in remote controller may have been exhausted.Replace the battery.
The time you have set with timer is incorrect.Wait or cancel timer setting.
Unit not cooling or heating (cooling/ heating models only) room very well while air flowing out from the air conditionerInappropriate temperature setting.Set temperature correctly.
Air filter is blocked.Clean the air filter.
Doors or windows are open.Close the doors or windows.
Air inlet or outlet of indoor or outdoor unit has been blocked.Clear obstructions away first, then restart the unit.
Compressor 3 minutes protection has been activated.Wait.

Carrier 50BV020-064 Heat Pump Troubleshooting

PROBLEMPOSSIBLE CAUSE
Control modules do not have lights when unit power is on.Transformer open. Circuit breaker open. Power wiring open. Module failure.
Control display does not light up when unit power is on.Connection location. Interface cable open. Display failure.
Run test will not start.Pre-existing ALARM (red)? Not ‘logged in” with password. Switch not in local.
WARN (yellow) LED does not light during run test.Wiring open. Lamp failure. Control module failure.
ALARM (red) LED does not light during run test.Wiring open. Lamp open. Control module failure.
Run test stops, ALARM (red) LED light is lit after it blinks once.Bypass switch to LINE. Mode switch to OFF. Duct high pressure switch open. Fire shutdown input or jumper open.
Supply air temp out of range. Duct static pressure sensor out of range. Compressor resistor board wiring error or failure.
Fan does not start/ALARM (red) LED blinks 2 times.Fan relay failure.
Run test stop, ALARM (red) LED is lit after blinking 3 times.Wiring open. VFD connection error. VFD setup error. Fan relay failure. Current isolator failure. Control module failure.
Run test stop, ALARM (red) LED is lit after it blinks 4 times. Fan does not increase speed.VFD connection error. VFD setup error. Current isolator load adjustment too low.
Fan does not stop after ALARM (red) LED blinks 5 times.Fan relay failure.
Fan rotation is backwards.VFD to motor wiring sequence error. VFD setup error.
Run test stop, ALARM (red) LED is lit after blinking 6 times. Compressor does not start.Wiring open. Compressor resistor board wiring error or failure. High pressure switch, low pressure switch, coil frost switch, or compressor protection module open. Compressor relay failure. Contactor failure. Control module failure. No refrigerant charge.
Run test stop, ALARM (red) LED is lit after blinking 7 times. Compressor 2 does not start.
Run test stop, ALARM (red) LED is lit after blinking 8 times. Compressor 3 does not start.
Run test stop, ALARM (red) LED is lit after blinking 9 times. Compressor 4 does not start.
Compressor rotation is backwards.Field power wiring sequence error. Compressor power wiring sequence error.
“C” message in I/O status display.No input signal or communication failure.
“Service’ message in I/O status display.Value is forced from 6400 keypad entry.
“Supervisor" message in I/O status display.Value is forced from network communication (i.e., PC).
ALARM (red) LED always on, will not enter run test.SAT, DSP, CSMUX, DHS, or PHASE input values. Mode switch OFF.

Carrier 50TFQ008-012 Heat Pump Troubleshooting

PROBLEMCAUSEREMEDY
Compressor Outdoor Fan Will Not Start.Power failure.Call power company.
Fuse blown or circuit breaker tripped.Replace fuse or reset circuit breaker.
Defective thermostat, contactor transformer or control relay.Replace component.
Insufficient line voltage.Determine cause and correct.
Incorrect or faulty wiring.Check wiring diagram and rewire correctly.
Thermostat setting too high.Lower thermostat setting below room temperature.
High-pressure switch tripped.
Low-pressure switch tripped.Check for leaks, repair, and recharge.
Freeze-up protection thermostat tripped.
Compressor Will Not Start But Outdoor Fan Runs.Faulty wiring or loose connections in compressor circuit.Check wiring and repair or replace.
Compressor motor burned out, seized, or internal overload open.Determine cause. Replace compressor.
Defective overload.Determine cause and replace.
One leg of 3-phase power dead.Replace fuse or reset circuit breaker. Determine cause.
Compressor Cycles (Other Than Normally Satisfying Thermostat).Refrigerant overcharge or undercharge.Recover refrigerant, evacuate system, and recharge to nameplate.
Defective compressor.Replace and determine cause.
Insufficient line voltage.Determine cause and correct.
Blocked outdoor coil or dirty air filter.
Defective overload.Determine cause and replace.
Defective thermostat.Replace thermostat.
Faulty outdoor-fan (cooling) or indoor-fan (heating) motor or capacitor.Replace.
Restriction in refrigerant system.Locate restriction and remove.
Compressor Operates Continuously.Dirty air filter.Replace filter.
Unit undersized for load.Decrease load or increase unit size.
Thermostat set too low.Reset thermostat.
Low refrigerant charge.Locate leak, repair, and recharge.
Leaking valves in compressor.Replace compressor.
Air in system.Recover refrigerant, evacuate system, and recharge.
Outdoor coil dirty or restricted.Clean coil or remove restriction.
Dirty air filter.Replace filter.

Carrier 38ANBK Heat Pump Troubleshooting

NO. OF QUICK LED FLASHESSYSTEM FAULT
2Room Air Thermistor
3Indoor Coil Thermistor
4Outdoor Coil Thermistor
5Compressor Malfunction
6Reversing Valve Malfunction
7Outdoor Air Thermistor*
8Indoor Fan Failure
9Discharge Air Thermistor

Carrier AQUAZONE 50PC Heat Pump Troubleshooting

ErrorCoolHeatChekCauseSolution
Excessively warm supply air temperature in cooling and/or excessively cool air in heatingXXAirflow too highFan speed setting too highConsult blower performance table and reduce fan speed if possible.
High or low water temperatureInlet water temperature out of rangeCheck unit capacity vs. water temperature.
Air leakageLeaky ductworkInspect ductwork.
Loss of refrigeration capacityLow refrigerantCheck refrigerant pressures with gage set.
Excessively cold supply air temperature in cooling or excessively hot supply air temperature in heatingXXReduced airflowDirty FilterReplace filter.
Fan speed too lowConsult blower performance table and increase fan speed if possible.
Excessive duct pressure dropConsult blower performance table and increase fan speed if possible.
No compressor or fan operationXXPower LED onBad thermostat connection / faulty thermostatCheck thermostat and wiring. "C\
Power LED offLow or no supply powerEnsure that the supply voltage to the unit is with in the range shown on the unit data plate.
Faulty control transformerCheck for 24 VAC between ‘R* and "C* on the unit terminal block. For 75 and 100 VA transformers, check that the transformer circuit breaker has not tripped. Check low voltage circuit for overload conditons or short circuits before replacing the transformer.
No fan operation - PSC motorXXFan relay energizedFaulty motorCheck supply voltage from the fan relay to the motor. Check that all motor wires are secure. With power off spin the motor shaft - noise, resistance or uneven motion can be signs of motor failure.
Fan relay not energizedNo fan operation signalCheck for 24 VAC across the fan relay coil. Check all wiring connections.
Bad fan relayIf the relay coil is energized but the relay does not pull in, check the resistance across the relay coil - an open circuit is an indicator of a faulty relay.
No fan operation - constant torque motorXXNo fan operation signalCheck all wiring connections.
Loose wiringCheck all wiring connections at motor and control box.
Faulty motorCheck supply voltage to the motor. Check that all motor wires are secure. With power off spin the motor shaft - noise, resistance or uneven motion can be signs of motor failure.
No fan operation - constant airflow motorXXNo fan operation signalCheck all wiring connections. Make sure that the thermostat connection plug is securely connected.
Loose wiringCheck all wiring connections at motor and control box. Check that power and control harnesses are securely connected.
Interface board problemsMake sure that the interface board is not damged and that all DIP switches are in the proper configuration
Faulty motorCheck supply voltage to the motor. Check that all motor wires are secure. Move the “TEST" DIP switch to *ON* and the other switches to "OFF* on the "ADJUST" switch block on the interface board With power off spin the motor shaft - noise, resistance or uneven motion can be signs of motor failure.
Unit not shifting into coolingXReversing valve solenoid energizedFaulty solenoidCheck that the reversing valve solenoid is receiving 24 VAC. If so, check the resistance of the solenoid - an open circuit may indicate a burned out solenoid.
Reversing valve solenoid not energizedMiswired/ faulty thermostatCheck that the reversing valve theromstat wire is connected to the “0‘ terminal of the thermostat
Check that the wires from the thermostat to the unit are securely connected and that the wires from the electrical box to the reversing valve are connected.

Carrier 50HCQA Heat Pump Troubleshooting

If Run LED shows...And Error LED shows...Status is...
2 flashes per secondOffNormal
2 flashes per second2 flashes, alternating with Run LEDFive minute auto-restart delay after system error
2 flashes per second3 flashes, then offControl module has just been formatted
2 flashes per second4 flashes, then pauseTwo or more devices on this network have the same ARC156 network address
2 flashes per secondOnExec halted after frequent system errors or control programs halted
5 flashes per secondOnExec start-up aborted, Boot is running
5 flashes per secondOffFirmware transfer in progress, Boot is runnin
7 flashes per second7 flashes per second, alternating wit Run LEDTen second recovery period after brownout
14 flashes per second14 flashes per second, alternating with Run LEDBrownout
OnOnFailure. Try the following solutions:
- Turn the RTU —MP off, then on.
- Format the RTU-MP.
- Download memory to the RTU-MR
- Replace the RTU —MP.

Carrier PTV Heat Pump Troubleshooting

FAULTDESCRIPTIONSOLUTION
Motor rocks slightly when startingThis is normal start-up for ECM.
Motor will not startNo movementCheck power at motor.
Check low voltage (24-vac R to C) at motor.
Check low voltage connections (G,Y. W, R. C) at motor.
Check for unseated pins in connectors on motor harness.
Test with a temporary jumper between R and G.
Check motor for tight shaft.
Perform motor/control replacement check.
Run moisture check.
Motor rocksCheck for loose or non-compliant motor mount.
Make sure blower wheel is tight on shaft.
Perform motor/control replacement check.
Motor oscillates up and down while being tested off of blowerIt is normal for motor to oscillate with no load on shaft.
Motor starts, but runs erraticallyVaries up and down or intermittentCheek line voltage for variation or “sag.”
Check low voltage connections (G,Y, W, R : C) at motor, unseated pins in motor harness connectors.
Check “Bk” for erratic cfm command (in variable speed applications).
Check system controls, thermostat.
Perform moisture check.
“Hunts” or “puffs” at high cfm (speed)If removing panel or filter reduces “puffing,” reduce restriction or reduce maximum airflow.
Stays at low cfm despite system call for cool or heat cfmCheck low voltage (thermostat) wires and connections.
Verify fan is not in delay mode. Wait until delay is complete.
Perform motor/control replacement check.
Stays at high cfmVerify fan is not in delay mode. Wait until delay is complete.
Perform motor/control replacement check.
Blower will not shut offCheck for Triac switched thermostat or solid state relay.
Excessive noiseNoisy blower or cabinetdetermine if it’s air, cabinet, duct, or motor noise.
Check for loose blower housing, panels, etc.
If high static is creating high blower speed, check for air whistling through seams in ducts, cabinets, or panels.
If high static is creating high blower speed, check for cabinet/duct deformaton.
“Hunts” or “puffs” at high cfm (speed)If removing panel or filter reduces “puffing,” reduce restriction or reduce maximum airflow.

Carrier PCV015 Heat Pump Troubleshooting

ProblemsHeatCoolCauseSolution
Main Power ProblemsXXGreen Status LED OffCheck line voltage circuit breaker and disconnect.
Check for line voltage between L1 and L2 on the contactor.
Check for 24 vac between R and C on controller.
Check primary/ secondary voltage on transformer.
HP Fault — Code 2 High PressureXReduced or no water flow in coolingCheck pump operation or valve operation/ setting.
Check water flow adjust to proper flow rate.
XWater temperature out of range in coolingBring water temperature within design parameters.
XReduced or no airflow in heatingCheck for dirty air filter and clean or replace.
Check fan motor operation and airflow restrictions.
Dirty air coil — construction dust etc.
External static too high. Check Tables 8-11.
XAir temperature out of range in heatingBring return-air temperature within design parameters.
XXOvercharged with refrigerantCheck superheat/ subcooling vs typical operating condition
XXBad HP switchCheck switch continuity and operation. Replace.
LP/LOC Fault — Code 3 Low Pressure/ Loss of ChargeXXInsufficient chargeCheck for refrigerant leaks.
XCompressor pump down at start-upCheck charge and start-up water flow.
FP1 Fault — Code 4 Water Freeze ProtectionXReduced or no water flow in heatingCheck pump operation or water valve operation/ setting.
Plugged strainer or filter. Clean or replace.
Check water flow adjust to proper flow rate.
XInadequate antifreeze levelCheck antifreeze density with hydrometer.
XImproper freeze protect set- ting (30 F vs 10 F)Clip JW2 jumper for antifreeze (10 F) use.
XWater temperature out of rangeBring water temperature within design parameters.
XXBad thermistorCheck temperature and impedance correlation.
FP2 Fault — Code 5 Air Coil Freeze ProtectionXReduced or no airflow in coolingCheck for dirty air filter and clean or replace.
Check fan motor operation and airflow restrictions.
External static too high.
XAir temperature out of rangeToo much cold vent air. Bring entering-air temperature within design parameters.
XImproper freeze protect set- ting (30 F vs 10 F)Normal airside applications will require 30 F only.
XXBad thermistorCheck temperature and impedance correlation.
Condensate Fault — Code 6XXBlocked drainCheck for blockade and clean drain.
XXImproper trapCheck trap dimensions and location ahead of vent.
xPoor drainageCheck for piping slope away from unit.
Check slope of unit toward outlet.
Poor anting. Check vent location.
xMoisture on sensorCheck for moisture shorting to air coil.
Over/ Under Voltage — Code 7 (Auto Resetting)xxUnder voltageCheck power supply and 24 vac voltage before and during operation.
Check power supply wire size.
Check compressor starting.
Check 24 vac and unit transformer tap for correct power supply voltage.
xxOver voltageCheck power supply voltage and 24 vac before and during operation.
Check 24 vac and unit transformer tap for correct power supply voltage.
Performance Monitor — Code 8xHeating mode FP2>125 FCheck for poor airflow or overcharged unit.
xCooling mode FP1>125 F OR FP2< 40 FCheck for poor water flow or airflow.