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Symptom Troubleshooting Index

SYMPTOM TROUBLESHOOTING INDEX

Symptom Diagnostic procedure Also check for
The blower and heater controls and the A/C system do not work
The A/C compressor clutch and the A/C condenser/radiator fans are inoperative, but the blower and heater controls work
The A/C compressor clutch does not engage, but the A/C condenser/ radiator fans operate, and the blower and heater controls work
The A/C condenser fan is inoperative, but the radiator fan runs with the A/C on. The blower and heater controls work normally
The A/C condenser fan runs with the A/C on, but the radiator fan is inoperative. The blower and heater controls work normally
The A/C condenser and radiator fans are inoperative with the A/C on. The blower and heater controls work normally
The A/C compressor clutch cycles rapidly on and off
  • Probable cause: A/C system is very low on refrigerant, indicating a possible leak
  • Do the refrigerant leak test (see REFRIGERANT LEAK CHECK ) and repair any leaks. Replace the receiver/dryer (see A/C LINE REPLACEMENT ), then recharge the system to specifications (see SYSTEM CHARGING )
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 condenser is malfunctioning
  • Recover A/C refrigerant (see REFRIGERANT RECOVERY ), then check the condenser for restrictions or poor airflow. Repair as needed. Recharge the system to specifications (see SYSTEM CHARGING )
  • Incorrect tension or abnormal wear on the drive belt. Replace the belt and/or the belt tensioner as needed.
  • Proper operation of the condenser/radiator fans. Repair as needed.
  • Signs of an overheated engine. Repair as needed.
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 test (see REFRIGERANT LEAK CHECK ) and repair any leaks. Recharge the system to specifications (see SYSTEM CHARGING )
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 test (see REFRIGERANT LEAK CHECK ) and repair any leaks. Replace the receiver/dryer (see A/C LINE REPLACEMENT ), then recharge the system to specifications (see SYSTEM CHARGING )
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 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, and there is frost on the expansion valve
  • HVAC DTCs (see GENERAL TROUBLESHOOTING INFORMATION )
  • Check the old expansion valve for contamination. If contaminants are found, replace the A/C system component that caused the contamination
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
  • HVAC DTCs (see GENERAL TROUBLESHOOTING INFORMATION )
  • Check the old expansion valve for contamination. If contaminants are found, replace the A/C system component that caused the contamination
Warm air comes out of the vents, but operation is normal otherwise
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: - Recirculation control motor circuit troubleshooting (see RECIRCULATION CONTROL MOTOR CIRCUIT TROUBLESHOOTING ) - Air mix control motor test (see )
Insufficient heating
  1. Check the coolant level
  2. Check the radiator cap (see RADIATOR CAP TEST )
  3. Check the coolant temperature during normal operation
  4. 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
  5. Do the air mix control motor test (see AIR MIX CONTROL MOTOR TEST )
  6. Check the blower motor unit for obstructions
  7. Check for air leaks around the ducts and vents
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