Diagnostic Starting Point - Heating, Ventilation and Air Conditioning

Diagnostic Starting Point - Heating, Ventilation and Air Conditioning

The heating, ventilation and air conditioning (HVAC) system is divided into 2 sections. The first Heating, Ventilation and Air Conditioning has all procedures that pertain to an HVAC component or function that are not specifically associated with an automatic or manual control system. The 2nd HVAC Systems - Manual has all procedures specific to the manual control system.

For systems with DTCs, begin the system diagnosis with the following procedure:

Refer to Diagnostic System Check - Vehicle. Initial Inspection and Diagnostic Overview

The Diagnostic System Check will provide the following information:

* The identification of the control modules which command the system.
* The ability of the control modules to communicate through the class 2 or GM LAN serial data circuit.

The use of the Diagnostic System Check will identify and lead the technician to the correct diagnostic procedure.

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
* Air Temperature Description and Operation

The Air Delivery Description and Operation contains the following topics:

* HVAC Control Components
* Air Speed
* Air Distribution
* Recirculation Operation

The Air Temperature Description and Operation contains the following topics:

* HVAC Control Components
* Heating and A/C Operation
* Engine Coolant
* A/C Cycle