Symptom Troubleshooting Index
SYMPTOM TROUBLESHOOTING CHART
| Symptom | Diagnostic procedure | Also check for |
|---|---|---|
| The blower and heater controls and the A/C system do not work | Probable cause: HVAC control malfunction Do the heater control power and ground circuit troubleshooting (see HEATER CONTROL POWER AND GROUND CIRCUIT TROUBLESHOOTING ) |
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| 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 switch circuit malfunction Troubleshoot the A/C pressure switch circuit (see A/C PRESSURE SWITCH CIRCUIT TROUBLESHOOTING ) |
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| 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 ) |
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| The A/C compressor clutch does not disengage when the A/C switch is off | Probable cause: The A/C compressor clutch circuit is on (energized) continuously, or the A/C compressor clutch is mechanically jammed
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The A/C compressor relief valve. If it has vented refrigerant to the atmosphere, correct the problem with the A/C compressor clutch or clutch circuit, then replace the relief valve (see A/C COMPRESSOR RELIEF VALVE REPLACEMENT ) |
| The A/C compressor relief valve has vented refrigerant | Probable cause: A high-side restriction, the A/C condenser/radiator fans are inoperative, or the A/C compressor clutch is not disengaging
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Powertrain DTCs (see GENERAL TROUBLESHOOTING INFORMATION ) |
| The A/C condenser fan is inoperative, but the radiator fan runs with the A/C on. The blower and heater controls work normally | Probable cause: A/C condenser fan circuit malfunction Do the A/C condenser fan circuit troubleshooting (see A/C CONDENSER FAN CIRCUIT TROUBLESHOOTING ) |
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| The A/C condenser and radiator fans are inoperative with the A/C on. The blower and heater controls work normally | Probable cause: Radiator/condenser fan common circuit malfunction Do the radiator and A/C condenser fan common circuit troubleshooting (see RADIATOR AND A/C CONDENSER FAN COMMON CIRCUIT TROUBLESHOOTING ) |
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| The A/C compressor clutch cycles rapidly on and off | Probable cause:
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| Warm air comes out of the vents. The suction line is cool to warm, and the discharge line is warm to hot | Probable cause: A/C system is low on refrigerant, indicating a possible leak Do the refrigerant leak check (see REFRIGERANT LEAK CHECK ) and repair any leaks. Recharge the system to specifications (see SYSTEM CHARGING ) |
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| Warm air comes out of the vents, and the high pressure liquid line is very hot | Probable causes: The A/C system is overcharged (too much refrigerant), or the A/C condenser is malfunctioning Recover A/C refrigerant (see REFRIGERANT RECOVERY ), then check the A/C condenser for restrictions or poor airflow. Repair as needed. Recharge the system to specifications (see SYSTEM CHARGING ) |
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| Warm air comes out of the vents. The suction line is cool to warm, the discharge line is warm to hot, and there is no frost on the expansion valve | Probable cause: Excessive air and/or moisture in the system, indicating a possible leak Do the refrigerant leak check (see REFRIGERANT LEAK CHECK ) and repair any leaks. Replace the receiver/dryer (see RECEIVER/DRYER DESICCANT REPLACEMENT ), then recharge the system to specifications (see SYSTEM CHARGING ) |
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| Warm air comes out of the vents. The liquid line or the condenser outlet is abnormally cool, or there is frost or condensation on the receiver/dryer | Probable cause: A restriction in the high-pressure side of the system Recover A/C refrigerant (see REFRIGERANT RECOVERY ), then check the liquid line, the receiver/dryer and the A/C condenser for restrictions. Repair as needed. Recharge the system to specifications (see SYSTEM CHARGING ) |
HVAC DTCs (see GENERAL TROUBLESHOOTING INFORMATION ) |
| There is heavy frost or condensation on the expansion valve, and frost on the suction line | Probable cause: A restriction in the low-pressure side of the system Recover A/C refrigerant (see REFRIGERANT RECOVERY ), then check the suction line, and the expansion valve for restrictions. Repair as needed. Recharge the system to specifications (see SYSTEM CHARGING ) |
HVAC DTCs (see GENERAL TROUBLESHOOTING INFORMATION ) |
| Warm air comes out of the vents, but A/C command is normal (A/C button and clutch are on) | Probable cause: Compressor failure Do the A/C system test (see A/C SYSTEM TEST ), and correct any problems. If necessary, replace the A/C compressor (see A/C COMPRESSOR REPLACEMENT ) |
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| Driver's and passenger's side vent temperatures vary by more than 20°F (11°C) | Probable causes: The recirculation control door or the air mix door is malfunctioning Do the following troubleshooting:
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| Warm air comes out of the vents, and there is frost on the expansion valve | Probable cause: The expansion valve is stuck closed Replace the expansion valve (see A/C COMPRESSOR REPLACEMENT ) |
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| The temperature of the liquid line is the same on both sides of the expansion valve, and the evaporator coil or suction line has heavy condensation | Probable cause: The expansion valve is stuck open Replace the expansion valve (see A/C COMPRESSOR REPLACEMENT ) |
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| Insufficient heating |
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