The heater and A/C programmer contains a microprocessor which controls the electronic A/C system. The programmer receives electrical signals from the following components:

A microprocessor in the programmer processes the signals. The microprocessor then sends commands to the system components that control the following elements:

The heater and A/C programmer also performs self-diagnosis functions for the electronic A/C system. When the system diagnostic mode is activated through a scan tool, these faults are displayed as a numeric diagnostic trouble code (DTC).