Initial Inspection and Diagnostic Overview

NOTE: This procedure applies to models equipped with the Automatic Zone Control (AZC) HVAC system. For testing of models not equipped with AZC, refer to Body Control Module for testing information.Testing and Inspection

The Automatic Zone Control (AZC) control module has a system self-diagnostic mode which continuously monitors various parameters during normal system operation. If a system fault is detected, a current and historical fault is recorded. When the current fault is cleared, the historical fault remains until reset (manually or automatically). Both the current and historical fault codes can be accessed through either the front panel, or over the Programmable Communications Interface (PCI) bus using a DRB III scan tool, and the appropriate diagnostic information.

The AZC control module is capable of three different types of self-diagnostic tests, as follows:
- Fault Code Tests
- Input Circuit Tests
- Output Circuit/Actuator Tests

Information in this section describes:
- How to read the self-diagnostic display
- How to enter the AZC control module self-diagnostic test mode
- How to select the self-diagnostic test types
- How to perform the different tests