GM Service Manual Online
For 1990-2009 cars only

Important: Review the system operation in order to familiarize yourself with the system functions. Refer to the following procedures:

   â€¢  Air Delivery Description and Operation
   â€¢  Air Temperature Description and Operation

Visual/Physical Inspection

    â€¢ Inspect for aftermarket devices which could affect the operation of the HVAC System. Refer to Checking Aftermarket Accessories .
    â€¢ Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
    â€¢ Verify the A/C compressor clutch turns freely and is not seized.
    â€¢ The A/C compressor will not operate in cold outside air temperatures. Refer to Air Temperature Description and Operation .
    â€¢ The following could cause window fogging:
       - Wet carpet or mats
       - High humidity
       - Interior water leak
       - Blocked A/C evaporator drain tube
       - Maximum passenger capacity
       - Blocked body pressure relief valves
    â€¢ Inspect the air distribution system for causes of reduced air flow:
       - Obstructed or dirty passenger compartment air filter, if equipped
       - Blocked or damaged air inlet or outlet vents

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

    â€¢  Air Conditioning Compressor Malfunction
    â€¢  Blower Motor Malfunction
    â€¢  Leak Testing
    â€¢  Noise Diagnosis - HVAC Module
    â€¢  Noise Diagnosis - Blower Motor
    â€¢  Odor Diagnosis