GM Service Manual Online
For 1990-2009 cars only

System Overview

The heater and A/C controls are available in the following 2 models:

With D55


Object Number: 305044  Size: SH

Without D55


Object Number: 305043  Size: MH

The climate control system automatically regulates and maintains the inside air temperatures from 18-29°C (65-85°F) regardless of the changes in the ambient air temperature. Settings of 16-32°C (60-90°F) provide unregulated heating and cooling.

The heater and A/C control selects a comfort level. The following main components comprise the climate control system:

    • The heater and A/C programmer, also called the air control module (ACM)
    • The powertrain control module (PCM)
    • The temperature sensors
    • The heating, ventilation, and air conditioning (HVAC) module
    • The refrigeration system

The climate control system is divided into the following 4 categories:

    • The general operation
    • The air delivery system
    • The refrigeration system
    • The temperature control system