AIR CONDITIONING & HEAT
AIR CONDITIONING TROUBLE SHOOTING
WARNING: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC AIR CONDITIONING TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE
Compressor Not Working • Compressor clutch circuit open.
Compressor clutch coil inoperative.
• Poor clutch ground connection.
Fan belts loose.
Thermostatic switch inoperative. Thermostatic switch not adjusted.
• Ambient temperature switch open.
Superheat fuse blown.
Excessive Noise or Vibration • Missing or loose mounting bolts.
• Bad idler pulley bearings.
Fan belts not tightened correctly. Compressor clutch contacting body. Excessive system pressure.
• Compressor oil level low.
Damaged clutch bearings.
Damaged reed valves.
Damaged compressor.
Insufficient or No Cooling;
Compressor Working • Expansion valve inoperative.
Heater control valve stuck open.
Low system pressure.
Blocked condenser fins.
Blocked evaporator fins.
Vacuum system leak.
Vacuum motors inoperative.
Control cables improperly adjusted.
Restricted air inlet.
Mode doors binding.
• Blower motor inoperative.
Temperature above system capacity.
HEATER SYSTEM TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting, refer to DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC HEATER SYSTEM TROUBLE SHOOTING CHART
CONDITION POSSIBLE CAUSE
Insufficient, Erratic,
or No Heat • Low Coolant Level
Incorrect thermostat.
Restricted coolant flow through
heater core.
Heater hoses plugged.
Misadjusted control cable.
Sticking heater control valve.
Vacuum hose leaking.
Vacuum hose blocked.
Vacuum motors inoperative.
Blocked air inlet.
Inoperative heater blower motor.
Oil residue on heater core fins.
Dirt on heater core fins.
Too Much Heat • Improperly adjusted cables.
• Sticking heater control valve.
No vacuum to heater control valve. Temperature door stuck open.
Air Flow Changes During
Acceleration • Vacuum system leak.
Bad check valve or reservoir.
Air From Defroster At All
Times • Vacuum system leak.
Improperly adjusted control cables.
• Inoperative vacuum motor.
Blower Does Not Operate
Correctly • Blown fuse.
• Blower motor windings open.
Resistors burned out.
Motor ground connection loose. Wiring harness connections loose.
Blower motor switch inoperative.
Blower relay inoperative.
Fan binding or foreign object
in housing.
Fan blades broken or bent.
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