How to Use the Self-Diagnostic Function With the HDS
- Make sure the ignition switch is in LOCK (0).
- Connect the HDS to the DLC.
- Turn the ignition switch to ON (II).
- Make sure the HDS communicates with the vehicle and the climate control unit. If it does not, go to the DLC circuit troubleshooting See DLC CIRCUIT TROUBLESHOOTING (EXCEPT K24Z7) or DLC CIRCUIT TROUBLESHOOTING (K24Z7) .
- Select HVAC/CLIMATE CONTROL in the BODY ELECTRICAL menu.
- Select INSPECTION in the HVAC/CLIMATE CONTROL menu.
- Select CLIMATE CONTROL SELF TEST in the INSPECTION menu.
- Check for DTCs. If any DTCs are indicated, write down the DTCs, then go to the indicated DTC troubleshooting. NOTE: After troubleshooting, clear the DTCs with the HDS. For specific operations, refer to the user's manual that came with the HDS.
How to Use the Self-Diagnostic Function Without the HDS
The climate control unit has a self-diagnostic function. To run the self-diagnostic function, do the following
Scheme 2
Scheme 2: How to Use the Self-Diagnostic Function Without the HDS
- Turn the ignition switch to LOCK (0), and then back to ON (II).
- Press and hold the ON/OFF button, then within 10 seconds press and release the REAR WINDOW DEFOGGER button five times. Release the ON/OFF button.
- ALL LCD segments come on for 2 seconds, then the self-diagnostic function begins. NOTE: The blower motor will run at various speeds regardless of what the panel is displaying. If there is any problem in the system, the system flashes 88 or alternately flashes 88. Refer to checking for DTCs. If there are no problems detected, the system will flashes no. Canceling the Self-Diagnostic Function
- Turn the ignition switch to LOCK (0) to cancel the self-diagnostic function. After completing repair work, run the self-diagnostic function again to make sure that there are no other DTCs.
How to check the past DTC's
The climate control unit can record DTCs of the past trouble. How to read the past DTC is as follows.
Scheme 3
Scheme 3: How to check the past DTC's
- Turn the ignition switch to LOCK (0), and then back to ON (II).
- Press and hold both the AUTO and ON/OFF buttons.
- During press and hold both the AUTO and ON/OFF buttons, and the past trouble is indicate. NOTE: If there is any problem in the system, the system flashes 88 or alternately flashes 88. Refer to checking for DTCs. If there are no problems detected, the system will flashes no. Canceling the read past DTC's
- Turn the ignition switch to LOCK (0), to cancel the read past DTC's. After completing the repair work, clear the DTCs.
How to clear the past DTC's
- Turn the ignition switch to LOCK (0).
- Press and hold both the AUTO and WINDSHIELD DEFROSTER buttons, then turn the ignition switch to ON (II).
- After about 5 seconds the windshield defroster indicator starts to blink, release the buttons. The indicator will blink 5 times then stop.
- Do the display DTC function to verify DTC's have been cleared.
How to Use the Self-Diagnostic Function
The HVAC control unit has a self-diagnostic function for the heating, ventilation, and air conditioning system. To run the self-diagnostic function, do the following
Scheme 4
Scheme 4: How to Use the Self-Diagnostic Function
Scheme 5
Scheme 6
- Turn the ignition switch to LOCK (0) and then back to ON (II).
- Set the fan control dial to OFF, temperature control dial to Max Cool, the VENTILATION button to ON.
- Press and hold the RECIRCULATION button, then within 10 seconds press and release the REAR WINDOW DEFOGGER/MIRROR DEFOGGER button five times. Release the RECIRCULATION button.
- The recirculation indicator turns on for 2 seconds, then the self-diagnostic function begins. NOTE: The blower motor will run at various speeds when in the self-diagnostic mode. Once the self-diagnostic function is finished, the recirculation indicator blinks, and the number of blinks indicates the Diagnostic Trouble Code (DTC) number. If there are multiple DTCs, the indicator blinks each DTC in sequence from the lowest DTC number to the highest. The indicator pauses 3 seconds, then repeats the DTC blink sequence. If no DTCs are found, the indicator will not blink. When the problem is repaired, the indicator will not blink. Example of DTC Indication Pattern (DTC 3) Example of DTCs Indication Pattern (DTC 2 and 4) DTC (Recirculation Indicator Blinks) Detection Item «1»(ref-614159-S31738191952014050700000) An open in the air mix control motor circuit «2»(ref-614159-S03008593902014050700000) A short in the air mix control motor circuit «3»(ref-614159-S25645644672014050700000) A problem in the air mix control motor circuit, linkage, door, or motor «4»(ref-614159-S37962760112014050700000) An open in the mode control motor circuit «5»(ref-614159-S13361231172014050700000) A short in the mode control motor circuit «6»(ref-614159-S00382728512014050700000) A problem in the mode control motor circuit, linkage, doors, or, motor «7»(ref-614159-S24406462382014050700000) An open in the recirculation control motor circuit «8»(ref-614159-S02120939582014050700000) A short in the recirculation control motor circuit «9»(ref-614159-S06946768262014050700000) A problem in the recirculation control motor circuit, linkage, door, or, motor «10»(ref-614159-S36909038892014050700000) A problem in the blower motor circuit «11»(ref-614159-S42060557532014050700000) HVAC control unit internal error «12»(ref-614159-S17106077352014050700000) An open in the evaporator temperature sensor circuit «13»(ref-614159-S37121390922014050700000) A short in the evaporator temperature sensor circuit Canceling the Self-Diagnostic Function
- Turn the ignition switch to LOCK (0), to cancel the self-diagnostic function. After completing the repair work, run the self-diagnostic function again to make sure that there are no other DTCs.
The HVAC control unit can record DTCs of the past trouble. How to read the past DTC is as follows.
Scheme 7
Scheme 7: How to check the past DTC's
Scheme 8
Scheme 9
- Turn the ignition switch to LOCK (0).
- Set the fan control dial to OFF, temperature control dial to Max Cool, the VENTILATION button to ON.
- Press and hold both the VENTILATION and the RECIRCULATION buttons, and turn the ignition switch ON (II).
- The vent indicator turns on for 2 seconds, then the past trouble is indicated. NOTE: In the case of multiple problems, the ventilation indicator will blink the lowest number DTC first. If no DTCs are found, the indicator will only blink two times. Example of DTC Indication Pattern (DTC 3) Example of DTCs Indication Pattern (DTC 2 and 4) DTC (Recirculation Indicator Blinks) Detection Item «1»(ref-614159-S31738191952014050700000) An open in the air mix control motor circuit «2»(ref-614159-S03008593902014050700000) A short in the air mix control motor circuit «3»(ref-614159-S25645644672014050700000) A problem in the air mix control motor circuit, linkage, door, or motor «4»(ref-614159-S37962760112014050700000) An open in the mode control motor circuit «5»(ref-614159-S13361231172014050700000) A short in the mode control motor circuit «6»(ref-614159-S00382728512014050700000) A problem in the mode control motor circuit, linkage, doors, or, motor «7»(ref-614159-S24406462382014050700000) An open in the recirculation control motor circuit «8»(ref-614159-S02120939582014050700000) A short in the recirculation control motor circuit «9»(ref-614159-S06946768262014050700000) A problem in the recirculation control motor circuit, linkage, door, or, motor «10»(ref-614159-S36909038892014050700000) A problem in the blower motor circuit «11»(ref-614159-S42060557532014050700000) HVAC control unit internal error «12»(ref-614159-S17106077352014050700000) An open in the evaporator temperature sensor circuit «13»(ref-614159-S37121390922014050700000) A short in the evaporator temperature sensor circuit Canceling the read past DTC's
- Turn the ignition switch to LOCK (0), to cancel the read past DTC's. After completing the repair work, clear the DTCs.
- Turn the ignition switch to LOCK (0).
- Set the fan control dial to OFF, temperature control dial to Max Cool, the VENTILATION button to ON.
- Press and hold the RECIRCULATION and WINDSHIELD DEFROSTER buttons, then turn the ignition switch to ON (II).
- After about 5 seconds the windshield defroster indicator starts to blink, release the buttons. The indicator will blink 5 times then stop.
- Do the display DTC function to verify DTC's have been cleared.
The heater control panel has a self-diagnostic function for the heating and ventilation system. To run the self-diagnostic function, do the following
Scheme 10
Scheme 10: How to Use the Self-Diagnostic Function
Scheme 11
Scheme 12
- Turn the ignition switch to LOCK (0) and then back to ON (II).
- Set the fan control dial to OFF, temperature control dial to Max Cool, the VENTILATION button to ON.
- Press and hold the RECIRCULATION button, then within 10 seconds press and release the REAR WINDOW DEFOGGER button five times. Release the RECIRCULATION button.
- The recirculation indicator turns on for 2 seconds, then the self-diagnostic function begins. NOTE: The blower motor will run at various speeds when in the self-diagnostic mode. Once the self-diagnostic function is finished, the recirculation indicator blinks, and the number of blinks indicates the Diagnostic Trouble Code (DTC) number. If there are multiple DTCs, the indicator blinks each DTC in sequence from the lowest DTC number to the highest. The indicator pauses 3 seconds, then repeats the DTC blink sequence. If no DTCs are found, the indicator will not blink. When the problem is repaired, the indicator will not blink. Example of DTC Indication Pattern (DTC 3) Example of DTCs Indication Pattern (DTC 2 and 4) DTC (Recirculation Indicator Blinks) Detection Item «1»(ref-614159-S31738191952014050700000) An open in the air mix control motor circuit «2»(ref-614159-S03008593902014050700000) A short in the air mix control motor circuit «3»(ref-614159-S25645644672014050700000) A problem in the air mix control motor circuit, linkage, door, or motor «4»(ref-614159-S37962760112014050700000) An open in the mode control motor circuit «5»(ref-614159-S13361231172014050700000) A short in the mode control motor circuit «6»(ref-614159-S00382728512014050700000) A problem in the mode control motor circuit, linkage, doors, or, motor «7»(ref-614159-S24406462382014050700000) An open in the recirculation control motor circuit «8»(ref-614159-S02120939582014050700000) A short in the recirculation control motor circuit «9»(ref-614159-S06946768262014050700000) A problem in the recirculation control motor circuit, linkage, door, or, motor «10»(ref-614159-S36909038892014050700000) A problem in the blower motor circuit «11»(ref-614159-S42060557532014050700000) Heater control panel internal error Canceling the Self-Diagnostic Function
- Turn the ignition switch to LOCK (0), to cancel the self-diagnostic function. After completing the repair work, run the self-diagnostic function again to make sure that there are no other DTCs.
The heater control panel can record DTCs of the past trouble. How to read the past DTC is as follows.
Scheme 13
Scheme 13: How to check the past DTC's
Scheme 14
Scheme 15
- Turn the ignition switch to LOCK (0).
- Set the fan control dial to OFF, temperature control dial to Max Cool, the VENTILATION button to ON.
- Press and hold both the VENTILATION and the RECIRCULATION buttons, and turn the ignition switch ON (II).
- The vent indicator turns on for 2 seconds, then the past trouble is indicated. NOTE: In the case of multiple problems, the ventilation indicator will blink the lowest number DTC first. If no DTCs are found, the indicator will only blink two times. Example of DTC Indication Pattern (DTC 3) Example of DTCs Indication Pattern (DTC 2 and 4) DTC (Recirculation Indicator Blinks) Detection Item «1»(ref-614159-S31738191952014050700000) An open in the air mix control motor circuit «2»(ref-614159-S03008593902014050700000) A short in the air mix control motor circuit «3»(ref-614159-S25645644672014050700000) A problem in the air mix control motor circuit, linkage, door, or motor «4»(ref-614159-S37962760112014050700000) An open in the mode control motor circuit «5»(ref-614159-S13361231172014050700000) A short in the mode control motor circuit «6»(ref-614159-S00382728512014050700000) A problem in the mode control motor circuit, linkage, doors, or, motor «7»(ref-614159-S24406462382014050700000) An open in the recirculation control motor circuit «8»(ref-614159-S02120939582014050700000) A short in the recirculation control motor circuit «9»(ref-614159-S06946768262014050700000) A problem in the recirculation control motor circuit, linkage, door, or, motor «10»(ref-614159-S36909038892014050700000) A problem in the blower motor circuit «11»(ref-614159-S42060557532014050700000) Heater control panel internal error Canceling the read past DTC's
- Turn the ignition switch to LOCK (0), to cancel the read past DTC's. After completing the repair work, clear the DTCs.
- Turn the ignition switch to LOCK (0).
- Set the fan control dial to OFF, temperature control dial to Max Cool, the VENTILATION button to ON.
- Press and hold the RECIRCULATION and WINDSHIELD DEFROSTER buttons, then turn the ignition switch to ON (II).
- After about 5 seconds the windshield defroster indicator starts to blink, release the buttons. The indicator will blink 5 times then stop.
- Do the display DTC function to verify DTC's have been cleared.
Climate Control System Symptom Troubleshooting Index
| Symptom | Diagnostic Procedure | Also Check for |
|---|
| The blower and the heater controls and the A/C system do not work | Probable cause: Climate control unit malfunction DO THE CLIMATE CONTROL POWER AND GROUND CIRCUIT TROUBLESHOOTING | Climate control DTCs See HOW TO TROUBLESHOOT THE BODY ELECTRICAL ('12) or HOW TO TROUBLESHOOT THE CLIMATE CONTROL SYSTEM Blown fuse No. B22 (7.5 A) in the under-dash fuse/relay box Poor ground at G504 Poor or loose connections at the terminals |
| The A/C compressor clutch and the A/C condenser/radiator fans are inoperative, but the blower and heater controls work | Probable cause: A/C pressure sensor circuit malfunction Troubleshoot the A/C pressure sensor circuit: A/C pressure sensor circuit low voltage See DTC TROUBLESHOOTING: P0532 ('12-'13: EXCEPT K24Z7) or DTC TROUBLESHOOTING: P0532 (K24Z7) A/C pressure sensor circuit high voltage See DTC TROUBLESHOOTING: P0533 ('12-'13: EXCEPT K24Z7) or DTC TROUBLESHOOTING: P0533 (K24Z7) NOTE: The A/C pressure sensor circuit can malfunction without setting a DTC | Climate control DTCs See HOW TO TROUBLESHOOT THE BODY ELECTRICAL ('12) or HOW TO TROUBLESHOOT THE CLIMATE CONTROL SYSTEM PGM-FI DTCs See HOW TO TROUBLESHOOT THE A/T SYSTEM , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (K24Z7) , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18A9) or HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18Z1) A/C signal circuit troubleshooting See A/C SIGNAL CIRCUIT TROUBLESHOOTING (KA KC KL MODELS WITH CLIMATE CONTROL) or A/C SIGNAL CIRCUIT TROUBLESHOOTING (KA KC KL MODELS WITH MANUAL A/C) Poor or loose connections at the terminals |
| The A/C compressor clutch does not engage, but the A/C condenser/radiator fans operate, and the blower and heater controls work | Probable cause: No power to the A/C compressor clutch Do the A/C compressor clutch circuit troubleshooting. | Climate control DTCs See HOW TO TROUBLESHOOT THE BODY ELECTRICAL ('12) or HOW TO TROUBLESHOOT THE CLIMATE CONTROL SYSTEM Blown fuse No. A25 (7.5 A) in the under-hood fuse/relay box Abnormal A/C system pressures A/C thermal protector has continuity Poor or loose connections at the terminals |
| The A/C condenser fan and/or the radiator fan do not run at low speed with the A/C on, but the blower and heater controls work normally | Probable cause: A/C condenser/radiator fan low speed circuit malfunction Do the radiator and A/C condenser fan low speed circuit troubleshooting See RADIATOR AND A/C CONDENSER FAN LOW SPEED CIRCUIT TROUBLESHOOTING (CLIMATE CONTROL (A/T, M/T)) or RADIATOR AND A/C CONDENSER FAN LOW SPEED CIRCUIT TROUBLESHOOTING (MANUAL A/C (A/T, M/T)) | Climate control DTCs See HOW TO TROUBLESHOOT THE BODY ELECTRICAL ('12) or HOW TO TROUBLESHOOT THE CLIMATE CONTROL SYSTEM PGM-FI DTCs See HOW TO TROUBLESHOOT THE A/T SYSTEM , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (K24Z7) , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18A9) or HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18Z1) Blown fuse No. A2-11 (20 A) in the under-hood fuse/relay box Poor ground at G301 Poor or loose connections at the terminals |
| The A/C condenser/radiator fans do not run at high speed, but do run at low speed with the A/C on | Probable cause: Malfunction in the fan(s) high speed circuit Do the following troubleshooting as needed: A/C condenser fan high speed circuit troubleshooting See A/C CONDENSER FAN HIGH SPEED CIRCUIT TROUBLESHOOTING (CLIMATE CONTROL (A/T, M/T)) or A/C CONDENSER FAN HIGH SPEED CIRCUIT TROUBLESHOOTING (MANUAL A/C (A/T, M/T)) RADIATOR FAN HIGH SPEED CIRCUIT TROUBLESHOOTING | Climate control DTCs See HOW TO TROUBLESHOOT THE BODY ELECTRICAL ('12) or HOW TO TROUBLESHOOT THE CLIMATE CONTROL SYSTEM PGM-FI DTCs See HOW TO TROUBLESHOOT THE A/T SYSTEM , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (K24Z7) , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18A9) or HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18Z1) Poor ground at G301 Poor or loose connections at the terminals |
| Blower fan runs slower than expected in cold weather (when in AUTO mode) NOTE: It is normal for the blower fan to run slowly until the coolant temperature rises when in AUTO mode | Probable cause: Engine coolant temperature (ECT) circuit malfunction Troubleshooting the ECT sensor circuit: ECT sensor 2 circuit low voltage See DTC TROUBLESHOOTING: P0117 ('12-'13: EXCEPT K24Z7) or DTC TROUBLESHOOTING: P0117 (K24Z7) ECT SENSOR 2 CIRCUIT HIGH VOLTAGE | Climate control DTCs See HOW TO TROUBLESHOOT THE BODY ELECTRICAL ('12) or HOW TO TROUBLESHOOT THE CLIMATE CONTROL SYSTEM PGM-FI DTCs See HOW TO TROUBLESHOOT THE A/T SYSTEM , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (K24Z7) , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18A9) or HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18Z1) Blower motor operation |
| The A/C compressor clutch cycles rapidly on and off | Probable cause: A/C system is overcharged Radiator and/or A/C condenser fan inoperative Excessive pressure on high side of system causing pressure sensor to turn A/C compressor off Thermal protector problem Low idle speed | Climate control DTCs See HOW TO TROUBLESHOOT THE BODY ELECTRICAL ('12) or HOW TO TROUBLESHOOT THE CLIMATE CONTROL SYSTEM |
| HDS does not communicate with the climate control unit or the vehicle | Troubleshoot the DLC circuit See DLC CIRCUIT TROUBLESHOOTING (EXCEPT K24Z7) or DLC CIRCUIT TROUBLESHOOTING (K24Z7) | |
| Insufficient heating | CHECK THE COOLANT LEVEL CHECK THE RADIATOR CAP Check the engine coolant temperature (ECT) during normal operation with the HDS Check the heater core inlet hose temperature: If it is COLD, check for restrictions in the hose, a damaged or leaking thermostat, or a damaged or leaking water pump If it is HOT, check for restrictions in the heater core. Back flush or replace the heater core See HEATER UNIT/CORE REMOVAL AND INSTALLATION (HEATING) , HEATER UNIT/CORE REMOVAL AND INSTALLATION (NATURAL GAS MODELS) or HEATER UNIT/CORE REMOVAL AND INSTALLATION (WITH A/C) DO THE AIR MIX CONTROL MOTOR TEST Check the blower motor unit for obstructions Check for air leaks around the ducts and vents | Climate control DTCs See HOW TO TROUBLESHOOT THE BODY ELECTRICAL ('12) or HOW TO TROUBLESHOOT THE CLIMATE CONTROL SYSTEM Damaged cylinder head gasket |
| NOTE |
|---|
| The A/C pressure sensor circuit can malfunction without setting a DTC |
| NOTE |
|---|
| It is normal for the blower fan to run slowly until the coolant temperature rises when in AUTO mode |
Heating and A/C Systems Symptom Troubleshooting Index
| Symptom | Diagnostic Procedure | Also Check for |
|---|
| The blower and the heater controls and the A/C system do not work | Probable cause: HVAC control unit malfunction DO THE HVAC CONTROL POWER AND GROUND CIRCUIT TROUBLESHOOTING | HVAC DTCS Blown fuse No. B22 (7.5 A) in the under-dash fuse/relay box Faulty blower motor relay Poor ground at G504 Poor or loose connections at the terminals |
| The A/C compressor clutch and the A/C condenser/radiator fans are inoperative, but the blower and heater controls work | Probable cause: A/C pressure sensor circuit malfunction Do the A/C pressure sensor troubleshooting: A/C pressure sensor circuit low voltage See DTC TROUBLESHOOTING: P0532 ('12-'13: EXCEPT K24Z7) or DTC TROUBLESHOOTING: P0532 (K24Z7) A/C pressure sensor circuit high voltage See DTC TROUBLESHOOTING: P0533 ('12-'13: EXCEPT K24Z7) or DTC TROUBLESHOOTING: P0533 (K24Z7) NOTE: The A/C pressure sensor circuit can malfunction without setting a DTC | HVAC DTCS PGM-FI DTCs See HOW TO TROUBLESHOOT THE A/T SYSTEM , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (K24Z7) , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18A9) or HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18Z1) A/C Signal Circuit Troubleshooting (KA KC KL models with Manual A/C) Poor or loose connections at the terminals |
| The A/C compressor clutch does not engage, but the A/C condenser/radiator fans operate, and the blower and heater controls work | Probable cause: No power to the A/C compressor clutch Do the A/C compressor clutch circuit troubleshooting See A/C COMPRESSOR CLUTCH CIRCUIT TROUBLESHOOTING (KA KC KL MODELS WITH CLIMATE CONTROL (A/T, M/T)) or A/C COMPRESSOR CLUTCH CIRCUIT TROUBLESHOOTING (KA KC KL MODELS WITH MANUAL A/C (A/T, M/T)) | HVAC DTCS Blown fuse No. A25 (7.5 A) in the under-hood fuse/relay box Abnormal A/C system pressures A/C thermal protector has continuity Poor or loose connections at the terminals |
| The A/C condenser fan and/or the radiator fan do not run at low speed with the A/C on, but the blower and heater controls work normally | Probable cause: A/C condenser/radiator fan low speed circuit malfunction Do the radiator and A/C condenser fan low speed circuit troubleshooting See RADIATOR AND A/C CONDENSER FAN LOW SPEED CIRCUIT TROUBLESHOOTING (CLIMATE CONTROL (A/T, M/T)) or RADIATOR AND A/C CONDENSER FAN LOW SPEED CIRCUIT TROUBLESHOOTING (MANUAL A/C (A/T, M/T)) | HVAC DTCS PGM-FI DTCs See HOW TO TROUBLESHOOT THE A/T SYSTEM , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (K24Z7) , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18A9) or HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18Z1) Blown fuse No. A2-10 (20 A) and/or No. A2-11 (20 A) in the under-hood fuse/relay box Poor ground at G301 Poor or loose connections at the terminals |
| The A/C condenser fan and/or the radiator fan do not run at high speed, but do run at low speed with the A/C on | Probable cause: Malfunction in the fan(s) high speed circuit Do the following troubleshooting as needed: A/C condenser fan high speed circuit troubleshooting See A/C CONDENSER FAN HIGH SPEED CIRCUIT TROUBLESHOOTING (CLIMATE CONTROL (A/T, M/T)) or A/C CONDENSER FAN HIGH SPEED CIRCUIT TROUBLESHOOTING (MANUAL A/C (A/T, M/T)) RADIATOR FAN HIGH SPEED CIRCUIT TROUBLESHOOTING | HVAC DTCS PGM-FI DTCs See HOW TO TROUBLESHOOT THE A/T SYSTEM , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (K24Z7) , HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18A9) or HOW TO TROUBLESHOOT THE FUEL AND EMISSIONS SYSTEMS (R18Z1) Poor ground at G301 Poor or loose connections at the terminals |
| The A/C compressor clutch cycles rapidly on and off | Probable cause: A/C system is overcharged Radiator and/or A/C condenser fan inoperative Excessive pressure on high side of system causing pressure sensor to turn A/C compressor off Thermal protector problem Low idle speed | HVAC DTCS |
| Insufficient heating | CHECK THE COOLANT LEVEL CHECK THE RADIATOR CAP Check the engine coolant temperature (ECT) during normal operation with the HDS Check the heater core inlet hose temperature: If it is COLD, check for restrictions in the hose, a damaged or leaking thermostat, or a damaged or leaking water pump If it is HOT, check for restrictions in the heater core. Back flush or replace the heater core See HEATER UNIT/CORE REMOVAL AND INSTALLATION (HEATING) , HEATER UNIT/CORE REMOVAL AND INSTALLATION (NATURAL GAS MODELS) or HEATER UNIT/CORE REMOVAL AND INSTALLATION (WITH A/C) DO THE AIR MIX CONTROL MOTOR TEST Check the blower motor unit for obstructions Check for air leaks around the ducts and vents | HVAC DTCS Damaged cylinder head gasket |
| NOTE |
|---|
| The A/C pressure sensor circuit can malfunction without setting a DTC |
Heating System Symptom Troubleshooting Index
| Symptom | Diagnostic Procedure | Also Check for |
|---|
| The blower and the heater controls do not work | Probable cause: Heater control panel malfunction DO THE HEATER CONTROL POWER AND GROUND CIRCUIT TROUBLESHOOTING | Blown the fuse No. B22 (7.5 A) in the under-dash fuse/relay box Faulty blower motor relay Poor ground at G504 Poor or loose connections at the terminals |
| Insufficient heating | CHECK THE COOLANT LEVEL CHECK THE RADIATOR CAP Check the engine coolant temperature (ECT) during normal operation with the HDS Check the heater core inlet hose temperature: If it is COLD, check for restrictions in the hose, a damaged or leaking thermostat, or a damaged or leaking water pump If it is HOT, check for restrictions in the heater core. Back flush or replace the heater core See HEATER UNIT/CORE REMOVAL AND INSTALLATION (HEATING) , HEATER UNIT/CORE REMOVAL AND INSTALLATION (NATURAL GAS MODELS) or HEATER UNIT/CORE REMOVAL AND INSTALLATION (WITH A/C) DO THE AIR MIX CONTROL MOTOR TEST Check the blower motor unit for obstructions Check for air leaks around the ducts and vents | HEATING DTCS Damaged cylinder head gasket |
Climate Control System DTC Troubleshooting Index
| DTC | Detection Item or Symptom | ECU | DTC type |
|---|
| U1280 | Communication bus line error (BUS-OFF) | Climate control unit | Loss of communication |
| DTC U128D | Lost communication with gauge control module (climate control unit) | Climate control unit | Loss of communication |
| B121A | An open in the mode control motor circuit | Climate control unit | Signal error |
| B121B | A short in the mode control motor circuit | Climate control unit | Signal error |
| B121D | Humidity/in-car temperature sensor communication error | Climate control unit | Loss of communication |
| B1220 | A short in the recirculation control motor circuit | Climate control unit | Signal error |
| B1227 | An open in the outside air temperature sensor circuit | Climate control unit | Signal error |
| B1228 | A short in the outside air temperature sensor circuit | Climate control unit | Signal error |
| B1229 | An open in the sunlight sensor circuit | Climate control unit | Signal error |
| B1230 | A short in the sunlight sensor circuit | Climate control unit | Signal error |
| B1231 | An open in the evaporator temperature sensor circuit | Climate control unit | Signal error |
| B1232 | A short in the evaporator temperature sensor circuit | Climate control unit | Signal error |
| B1233 | An open in the air mix control motor circuit | Climate control unit | Signal error |
| B1234 | A short in the air mix control motor circuit | Climate control unit | Signal error |
| B1235 | A problem in the air mix control motor circuit, linkage, door, or motor | Climate control unit | Signal error |
| B1240 | A problem in the mode control motor circuit, linkage, doors, or motor | Climate control unit | Signal error |
| B1241 | A problem in the blower motor circuit | Climate control unit | Signal error |
| B2983 | A problem in the recirculation control motor circuit, linkage, door, or motor | Climate control unit | Signal error |
| B2986 | An open in the recirculation control motor circuit | Climate control unit | Signal error |
Scheme 16
Scheme 16: Climate Control Unit Inputs and Outputs
| Cavity | Wire Color | Terminal Name | Description | Signal |
|---|
| 1 | GRY | ILLUMI+ | Power source for illumination | With combination light switch ON: battery voltage |
| 2 | Not used | Not used | | |
| 3 | PNK | M-HOT | Outputs to drive air mix control motor to HOT side | With ignition switch ON (II), air mix control motor moving to HOT: battery voltage |
| 4 | LT BLU | M-COOL | Outputs to drive air mix control motor to COOL side | With ignition switch ON (II), air mix control motor moving to COOL: battery voltage |
| 5 | GRN | MODE_MTR_DEF | Outputs to drive mode control motor to DEF side | With ignition switch ON (II), and mode control motor moving to DEF: battery voltage |
| 6 | WHT | MODE_MTR_VENT | Outputs to drive mode control motor to VENT side | With ignition switch ON (II), and mode control motor moving to VENT: battery voltage |
| 7 | PUR | F/R_MTR (FRESH) | Outputs to drive recirculation control motor to FRESH side | With ignition switch ON (II), and recirculation control motor moving to FRESH: battery voltage |
| 8 | ORN | F/R_MTR (REC) | Outputs to drive recirculation control motor to RECIRCULATE side | With ignition switch ON (II), and recirculation control motor moving to RECIRCU: battery voltage |
| 9 | GRN | RFD-P | Detects potentiometer signal of recirculation control motor | With ignition switch ON (II): about 0.5-4.5 V (depending on recirculation control motor position) |
| 10 | GRY | AMD-P | Detects potentiometer signal of air mix control motor | With ignition switch ON (II): about 0.5-4.0 V (depending on air mix control motor position) |
| 11 | PUR | MDD-P | Detects potentiometer signal of mode control motor | With ignition switch ON (II): about 0.5-4.5 V (depending on mode control motor position) |
| 12 | YEL | BLOWER_G | Outputs power transistor gate voltage | With ignition switch ON (II), and fan control switch OFF: less than 0.2 V With ignition switch ON (II), and fan control switch ON: about 4.0 V-battery voltage (depending on blower motor control) |
| 13 | BLU | BLOWER_V | Feedback signal of power transistor drain voltage | With ignition switch ON (II): about 0 V-battery voltage (depending on blower motor speed) |
| 14 | BRN | TEVA | Detects evaporator temperature sensor signal | With ignition switch ON (II): about 1.0-4.0 V (depending on evaporator temperature) |
| 15 | Not used | Not used | | |
| 16 | BLK | S_5V | Outputs sensor 5 V | With ignition switch ON (II): about 5.0 V |
| 17 | LT GRN | IG2_A/C | IG2 power source | With ignition switch ON (II): battery voltage |
| 18 | BLU | TAM | Detects outside air temperature sensor signal | With ignition switch ON (II): about 1.0-4.0 V (depending on outside air temperature) |
| 19 | BLK | GND | Ground for climate control unit (G504) | Less than 0.2 V at all times |
| 20 | RED | SENSOR_COM | Sensor ground | Less than 0.2 V at all times |
| 21 | PUR | TSUN | Detects sunlight sensor signal | With ignition switch ON (II), sunlight sensor out of direct sunlight: 3.56 V or more With ignition switch ON (II), sunlight sensor in direct sunlight: less than 3.56 V |
| 22 | YEL | HUM_DATA | Humidity sensor communication signal | With ignition switch ON (II): pulses |
| 23 | LT BLU | TR | TR communication signal | With ignition switch ON (II): pulses |
| 24 | BRN | RR_DEF_RLY_CL | Signal for rear window defogger relay | With ignition switch ON (II), and rear window defogger button ON: about 0 V With ignition switch ON (II), and rear window defogger button OFF: battery voltage |
| 25 | BLU | THERMAL_PRT | Outputs A/C on/off signal | With ignition switch ON (II), normal A/C pressure, and A/C switch OFF: battery voltage With ignition switch ON (II), normal A/C pressure, and A/C switch ON: less than 0.2 V |
| 26 | PNK | B_CAN-H | B_CAN-H communication signal | With ignition switch ON (II): pulses |
| 27 | BLU | B_CAN-L | B_CAN-L communication signal | With ignition switch ON (II): pulses |
| 28 | Not used | Not used | | |
| 29 | Not used | Not used | | |
| 30 | Not used | Not used | | |
| 31 | Not used | Not used | | |
| 32 | BLU | ILL- (LED) | Detects illumination control signal | With combination light switch ON: changed voltage (depending on dashlights brightness controller) |
Scheme 17
Scheme 17: Climate Control Unit Power and Ground Circuit Troubleshooting
Note. Do this troubleshooting procedure only if sent here by symptom troubleshooting.
Scheme 18
Scheme 19
- Fuse check: 1. Check the following fuse. Fuse No. B22 (7.5 A) Location Under-dash fuse/relay box Is the fuse OK? YES: Go to step 2. NO: Replace the fuse. If the fuse blows again, repair a short to ground in the No. B22 (7.5 A) fuse circuit.
- Open wire check (IG2_A/C line): 1. Disconnect the following connector. Climate control unit 32P connector 2. Turn the ignition switch to ON (II). 3. Measure the voltage between test points 1 and 2. Test condition IG ON (II) Climate control unit 32P connector: disconnected Test circuit IG2_A/C Test point 1 Climate control unit 32P connector No. 17 (LT GRN) Test point 2 Body ground Is there battery voltage? YES: The IG2_A/C wire is OK. Go to step 3. NO: Repair an open in the IG2_A/C wire between the under-dash fuse/relay box No. B22 (7.5 A) fuse and the climate control unit.
- Open wire check (GND line): 1. Turn the ignition switch to LOCK (0). 2. Check for continuity between test points 1 and 2. Test condition IG LOCK (0) Climate control unit 32P connector: disconnected Test circuit GND Test point 1 Climate control unit 32P connector No. 19 (BLK) Test point 2 Body ground Is there continuity? YES: The GND wire is OK. Replace the climate control unit. NO: Check for an open in the wire between the climate control unit and body ground. If the wire is OK, check for poor ground at G504.
Scheme 20
Scheme 20: Heater Control Power and Ground Circuit Troubleshooting
Note. Do this troubleshooting procedure only if sent here by symptom troubleshooting.
Scheme 21
Scheme 22
- Fuse check: 1. Check the following fuse. Fuse No. B22 (7.5 A) Location Under-dash fuse/relay box Is the fuse OK? YES: Go to step 2. NO: Replace the fuse. If the fuse blows again, repair a short to ground in the No. B22 (7.5 A) fuse circuit.
- Open wire check (IG2_A/C line): 1. Disconnect the following connector. Heater control panel 32P connector 2. Turn the ignition switch to ON (II). 3. Measure the voltage between test points 1 and 2. Test condition IG ON (II) Heater control panel 32P connector: disconnected Test circuit IG2_A/C Test point 1 Heater control panel 32P connector No. 17 (LT GRN) Test point 2 Body ground Is there battery voltage? YES: The IG2_A/C wire is OK. Go to step 3. NO: Repair an open in the IG2_A/C wire between the under-dash fuse/relay box No. B22 (7.5 A) fuse and the heater control panel.
- Open wire check (GND line): 1. Turn the ignition switch to LOCK (0). 2. Check for continuity between test points 1 and 2. Test condition IG LOCK (0) Heater control panel 32P connector: disconnected Test circuit GND Test point 1 Heater control panel 32P connector No. 19 (BLK) Test point 2 Body ground Is there continuity? YES: The GND wire is OK. «REPLACE THE HEATER CONTROL PANEL»(ref-614128-S20941649542014050700000) . NO: Check for an open in the wire between the heater control panel and body ground. If the wire is OK, check for poor ground at G504.
Note. Before testing the sensor, check for climate control DTCs.
Scheme 23
Scheme 24
- Humidity Sensor - Test NOTE: The climate control unit receives humidity (%) data via digital transmission. Turn the ignition switch to LOCK (0). Press and hold both the AUTO (A) and RECIRCULATION CONTROL (B) buttons, then start the engine. After the engine starts, release both buttons. The climate control unit will flash the sensor number and then the value for that sensor. Press the REAR WINDOW DEFOGGER/MIRROR DEFOGGER button (C) until the b (humidity) is displayed. For details about the displayed content. If the value is far from the actual humidity, replace the humidity/in-car temperature sensor.
- In-Car Temperature Sensor - Test NOTE: The climate control unit receives in-car temperature (°C) data via digital transmission. Turn the ignition switch to LOCK (0). Press and hold both the AUTO (A) and RECIRCULATION CONTROL (B) buttons, then start the engine. After the engine starts, release both buttons. The climate control unit will flash the sensor number and then the value for that sensor. Press the REAR WINDOW DEFOGGER/MIRROR DEFOGGER button (C) until the 2 (in-car temperature) is displayed. For details about the displayed content. If the value is far from the actual in-car temperature, replace the humidity/in-car temperature sensor.
Scheme 25
Scheme 25: HVAC Control Power and Ground Circuit Troubleshooting
Note. Do this troubleshooting procedure only if sent here by symptom troubleshooting.
Scheme 26
Scheme 27
- Fuse check: 1. Check the following fuse. Fuse No. B22 (7.5 A) Location Under-dash fuse/relay box Is the fuse OK? YES: Go to step 2. NO: Replace the fuse. If the fuse blows again, repair a short to ground in the No. B22 (7.5 A) fuse circuit.
- Open wire check (IG2_A/C line): 1. Disconnect the following connector. HVAC control unit 32P connector 2. Turn the ignition switch to ON (II). 3. Measure the voltage between test points 1 and 2. Test condition IG ON (II) HVAC control unit 32P connector: disconnected Test circuit IG2_A/C Test point 1 HVAC control unit 32P connector No. 17 (LT GRN) Test point 2 Body ground Is there battery voltage? YES: The IG2_ A/C wire is OK. Go to step 3. NO: Repair an open in the IG2_A/C wire between the under-dash fuse/relay box No. B22 (7.5 A) fuse and the HVAC control unit.
- Open wire check (GND line): 1. Turn the ignition switch to LOCK (0). 2. Check for continuity between test points 1 and 2. Test condition IG LOCK (0) HVAC control unit 32P connector: disconnected Test circuit GND Test point 1 HVAC control unit 32P connector No. 19 (BLK) Test point 2 Body ground Is there continuity? YES: The GND wire is OK. Replace the HVAC control unit See «HVAC CONTROL UNIT REMOVAL AND INSTALLATION (WITH NAVIGATION)»(ref-614128-S33933720352014050700000) or «HVAC CONTROL UNIT REMOVAL AND INSTALLATION (WITHOUT NAVIGATION)»(ref-614128-S26402621222014050700000) . NO: Check for an open in the wire between the HVAC control unit and body ground. If the wire is OK, check for poor ground at G504.
Scheme 28
Scheme 28: HVAC Control Unit Connector for Inputs and Outputs
| Cavity | Wire Color | Terminal Name | Description | Signal |
|---|
| 1 | GRY | ILLUMI+ | Power source for illumination | With combination light switch ON: battery voltage |
| 2 | Not used | Not used | | |
| 3 | BLU | ILL-(LED) | Detects illumination control signal | With combination light switch ON: changed voltage (depending on dashlights brightness controller) |
| 4 | Not used | Not used | | |
| 5 | PNK | M-HOT | Outputs to drive air mix control motor to HOT side | With ignition switch ON (II) and air mix control motor moving to HOT: battery voltage |
| 6 | LT BLU | M-COOL | Outputs to drive air mix control motor to COOL side | With ignition switch ON (II) and air mix control motor moving to COOL: battery voltage |
| 7 | GRN | MODE_MTR_DEF | Outputs to drive air mix control motor to DEF side | With ignition switch ON (II) and mode control motor moving to DEF: battery voltage |
| 8 | WHT | MODE_MTR_VENT | Outputs to drive mode control motor to VENT side | With ignition switch ON (II) and mode control motor moving to VENT: battery voltage |
| 9 | PUR | F/R_MTR (FRESH) | Outputs to drive recirculation control motor to FRESH side | With ignition switch ON (II) and recirculation control motor moving to FRESH: battery voltage |
| 10 | ORN | F/R_MTR (REC) | Outputs to drive recirculation control motor to RECIRCULATE side | With ignition switch ON (II) and recirculation control motor moving to RECIRCU: battery voltage |
| 11 | Not used | Not used | | |
| 12 | GRN | RFD-P | Detects potentiometer signal of recirculation control motor | With ignition switch ON (II): about 0.5-4.5 V (depending on recirculation control motor position) |
| 13 | GRY | AMD-P | Detects potentiometer signal of air mix control motor | With ignition switch ON (II): about 0.5-4.0 V (depending on air mix control motor position) |
| 14 | PUR | MDD-P | Detects potentiometer signal of mode control motor | With ignition switch ON (II): about 0.5-4.5 V (depending on mode control motor position) |
| 15 | Not used | Not used | | |
| 16 | BLK | S_5V | Outputs sensor 5 V | With ignition switch ON (II): about 5.0 V |
| 17 | LT GRN | IG2_A/C | IG2 power source | With ignition switch ON (II): battery voltage |
| 18 | Not used | Not used | | |
| 19 | BLK | GND | Ground for HVAC control unit (G504) | With ignition switch ON (II): less than 0.2 V |
| 20 | RED | SENSOR_COM | Sensor ground | With ignition switch ON (II): less than 0.2 V |
| 21 | Not used | Not used | | |
| 22 | YEL | BLOWER_G | Outputs power transistor gate voltage | With ignition switch ON (II) and fan control dial OFF: less than 0.2 V With ignition switch ON (II) and fan control dial ON: about 4.0 V-battery voltage (depending on blower motor control) |
| 23 | Not used | Not used | | |
| 24 | BLU | BLOWER_V | Feedback signal of power transistor drain voltage | With ignition switch ON (II): about 0 V-battery voltage (depending on blower motor speed) |
| 25 | Not used | Not used | | |
| 26 | BRN | RR_DEF_RLY_CL | Signal for rear window defogger relay | With ignition switch ON (II) and rear window defogger button ON: about 0 V With ignition switch ON (II) and rear window defogger button OFF: battery voltage |
| 27 (1) | BLU | THERMAL_PRT | Outputs A/C on/off signal | With ignition switch ON (II), normal A/C pressure, and A/C switch OFF: battery voltage With ignition switch ON (II), normal A/C pressure, and A/C switch ON: less than 0.2 V |
| 27 (2) | RED | ACS | Outputs A/C on/off signal | With ignition switch ON (II), normal A/C pressure, and A/C switch OFF: battery voltage With ignition switch ON (II), normal A/C pressure, and A/C switch ON: less than 0.2 V |
| 28 | BLU | A/C_CUT | Outputs A/C off prohibition signal | With ignition switch ON (II) and when HAC CUT control is prohibited: battery voltage With ignition switch ON (II) and when HAC CUT control is permitted: less than 0.2 V |
| 29 | Not used | Not used | | |
| 30 | PNK | ECON_SW | Inputs E-CON control signal | With ignition switch ON (II) and ECON OFF mode: battery voltage With ignition switch ON (II) and ECON ON mode: less than 1.0 V |
| 31 | Not used | Not used | | |
| 32 | BRN | TEVA | Detects evaporator temperature sensor signal | With ignition switch ON (II): about 1.0-4.0 V (depending on evaporator temperature) |
| (1) USA and Canada models (2) Mexico models |
Mode Control Motor Test
SPECIAL TOOL DESCRIPTION Image Description/Tool Number Backprobe Set 07SAZ-001000A (2)
Scheme 29
Scheme 29: Mode Control Motor Test
Scheme 30
Scheme 31
- Glove Box Remove the bolts (A). Remove the glove box (A).
Note. Before testing the motor, check for HVAC DTCs.
Scheme 32
- Mode Control Motor - Test Disconnect the mode control motor connector. NOTE: Incorrectly applying power and ground to the mode control motor will damage it. Follow the instructions carefully. Connect battery power to terminal No. 6 of the mode control motor, and ground terminal No. 7; the mode control motor should run, and stop at Defrost. If it does not, reverse the connections; the mode control motor should run, and stop at Vent. When the mode control motor stops running, disconnect battery power immediately. If the mode control motor did not run in step 2, remove it, then check the mode control linkage and door for smooth movement. If the linkage and door move smoothly, go to step 4. If the linkage or door sticks or binds, repair them as needed. Measure the resistance between terminals No. 1 and No. 3. It should be between 4.2 to 7.8 kohms. Reconnect the mode control motor connector. Turn the ignition switch to ON (II). Using the backprobe set, measure the voltage between terminals No. 3 and No. 5 (2-door) or No. 2 (4-door). Vent: About 0.5 V Defrost: About 4.5 V If either the resistance or the voltage readings are not as specified, replace the mode control motor.
Scheme 33
Scheme 34
- Glove Box Install the glove box (A). Install the bolts (A).
A/C System Test Result (Climate Control)
| Test Results | Related Symptoms | Probable Cause |
|---|
| Discharge pressure abnormally High | Discharge pressure reduced when A/C condenser cooled with water spray With doors open, fresh air selected, and radiator and A/C condenser fan run on high speed, temperature drop across A/C condenser inlet to outlet is less than about 41 °F (5 °C) while A/C compressor is running | Significant refrigerant overcharge |
| Restricted/weak airflow through A/C condenser | Dirty A/C condenser or damaged fins Debris between A/C condenser and radiator One or more cooling fans malfunctioning |
| Discharge pressure abnormally Low | Suction and discharge pressures equalize rapidly after stopping A/C compressor Suction pressure higher than normal | Faulty A/C compressor discharge valve or seal |
| Suction pressure abnormally Low | Weak or insufficient airflow across evaporator | Restricted blower intake or dust and pollen filter |
| Suction pressure varies from near normal to a vacuum, as moisture freezes in expansion valve orifice | Moisture in the system Faulty expansion valve |
| Reduced airflow from vents Vent temperature is very low | Condensation freezing on evaporator Faulty evaporator temperature sensor (check DTC) Faulty expansion valve or A/C compressor clutch relay |
| Suction pressure abnormally High | Lack of slight suction pressure variation at 1, 500 RPM when "Recirculated" airflow is switched to "Fresh Air" Discharge pressure near normal | Expansion valve stuck open or open too long |
| Suction and Discharge pressures abnormally High | A sheet of paper does not stick to front of A/C condenser surface with cooling fans on With doors open, fresh air selected and radiator and A/C condenser fan run on high speed, temperature drop across A/C condenser inlet to outlet is less than about 41 °F (5 °C) | One (or both) cooling fan motor inoperative or wires reversed |
| A/C compressor clutch remains engaged during off cycle A/C compressor relief valve may open | Insufficient A/C compressor clutch clearance A/C compressor clutch relay or circuit problem Excessive air in system |
| Suction and Discharge pressures abnormally Low | Suction line from expansion valve to A/C compressor is not cold | Excessively low refrigerant charge |
| Lack of slight suction pressure variation at 1, 500 RPM when "Recirculated" airflow is switched to "Fresh Air" | Expansion valve clogged with debris/desiccant, stuck closed, or not opening sufficiently |
| More than 50-60 °F (10-16 °C) temperature drop across A/C condenser inlet to outlet pipes | Blocked or restricted A/C condenser internal passages or lines/components restricting refrigerant flow |
| Significant temperature difference along high or low side A/C lines or components NOTE: Some restrictions may not show up until 3, 000 RPM | Restriction in A/C suction or discharge lines or components (check temperatures to isolate) |
| Suction pressure High and Discharge pressure Low | Excessive A/C compressor noise Pressures equalize quickly and noise after A/C compressor turns off | A/C compressor internal damage (Check for A/C system debris contamination) |
| Suction and discharge pressures normal (or near normal) | Vent temperature too high | Slightly low refrigerant charge Air mix door sticking, misadjusted or inoperative Excessive refrigerant oil in system |
| Static pressures high with A/C system equalized. (After engine is off 4-12 hours) | Air/Non-condensable gasses in system Contaminated or incorrect refrigerant |
| NOTE |
|---|
| Some restrictions may not show up until 3, 000 RPM |
A/C System Test Result (Manual A/C)
| Test Results | Related Symptoms | Probable Cause |
|---|
| Discharge pressure abnormally High | Discharge pressure reduced when A/C condenser cooled with water spray With doors open, fresh air selected, and radiator and A/C condenser fan run on high speed, temperature drop across A/C condenser inlet to outlet is less than about 41 °F (5 °C) while A/C compressor is running | Significant refrigerant overcharge |
| Restricted/weak airflow through A/C condenser | Dirty A/C condenser or damaged fins Debris between A/C condenser and radiator One or more cooling fans malfunctioning |
| Discharge pressure abnormally Low | Suction and discharge pressures equalize rapidly after stopping A/C compressor Suction pressure higher than normal | Faulty A/C compressor discharge valve or seal |
| Suction pressure abnormally Low | Weak or insufficient airflow across evaporator | Restricted blower intake or dust and pollen filter |
| Suction pressure varies from near normal to a vacuum, as moisture freezes in expansion valve orifice | Moisture in the system Faulty expansion valve |
| Reduced airflow from vents Vent temperature is very low | Condensation freezing on evaporator Faulty evaporator temperature sensor (check DTC) Faulty expansion valve or A/C compressor clutch relay |
| Suction pressure abnormally High | Lack of slight suction pressure variation at 1, 500 RPM when "Recirculated" airflow is switched to "Fresh Air" Discharge pressure near normal | Expansion valve stuck open or open too long |
| Suction and Discharge pressures abnormally High | A sheet of paper does not stick to front of A/C condenser surface with cooling fans on With doors open, fresh air selected and radiator and A/C condenser fan run on high speed, temperature drop across A/C condenser inlet to outlet is less than about 41 °F (5 °C) | One (or both) cooling fan motor inoperative or wires reversed |
| A/C compressor clutch remains engaged during off cycle A/C compressor relief valve may open | Insufficient A/C compressor clutch clearance A/C compressor clutch relay or circuit problem Excessive air in system |
| Suction and Discharge pressures abnormally Low | Suction line from expansion valve to A/C compressor is not cold | Excessively low refrigerant charge |
| Lack of slight suction pressure variation at 1, 500 RPM when "Recirculated" airflow is switched to "Fresh Air" | Expansion valve clogged with debris/desiccant, stuck closed, or not opening sufficiently |
| More than 50-60 °F (10-16 °C) temperature drop across A/C condenser inlet to outlet pipes | Blocked or restricted A/C condenser internal passages or lines/components restricting refrigerant flow |
| Significant temperature difference along high or low side A/C lines or components NOTE: Some restrictions may not show up until 3, 000 RPM | Restriction in A/C suction or discharge lines or components (check temperatures to isolate) |
| Suction pressure High and Discharge pressure Low | Excessive A/C compressor noise Pressures equalize quickly and noise after A/C compressor turns off | A/C compressor internal damage (Check for A/C system debris contamination) |
| Suction and discharge pressures normal (or near normal) | Vent temperature too high | Slightly low refrigerant charge Air mix door sticking, misadjusted or inoperative Excessive refrigerant oil in system |
| Static pressures high with A/C system equalized. (After engine is off 4-12 hours) | Air/Non-condensable gasses in system Contaminated or incorrect refrigerant |
| NOTE |
|---|
| Some restrictions may not show up until 3, 000 RPM |
