The heating, ventilation and air conditioning (HVAC) system is divided into 3 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. The third, HVAC Systems - Automatic, has all the procedures specific to the automatic control system.
For systems with DTCs, begin the system diagnosis with the following procedure:
Refer to
Diagnostic System Check - Vehicle
.
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:
The Air Delivery Description and Operation contains the following topics:
| • | HVAC Control Components |
| • | Recirculation Operation |
The Air Temperature Description and Operation contains the following topics:
| • | HVAC Control Components |
| • | Heating and A/C Operation |
