GM Service Manual Online
For 1990-2009 cars only

The Heating, Ventilation and Air Conditioning (HVAC) system is divided into two separate sections. The first, Heating, Ventilation and Air Conditioning, has all procedures that pertain to a HVAC component or function that is not specifically associated with the manual control system. The second, HVAC Systems - Manual, has all procedures specific to the manual control system.

Begin the system diagnosis with the Diagnostic System Check - HVAC Systems - Manual in HVAC Systems - Manual for a system with DTCs

The Diagnostic System Check will provide the identification of the control module(s) which command the system.

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and where the procedure is located.

Review the Description and Operation information to help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the Description and Operation information will also help you determine if the condition described by the customer is normal operation. The HVAC Description and Operation information is divided into:

    •  Air Delivery Description and Operation in HVAC Systems - Manual
    •  Air Temperature Description and Operation in HVAC Systems - Manual

The Air Delivery Description and Operation contains the following topics:

    • Air Speed
    • Air Distribution

The Air temperature Description and Operation contains the following topics:

    • Heater Mode
    • A/C Mode
    • A/C Cycle