Control Module HVAC: Description and Operation

HVAC PROGRAMMER DESCRIPTION

HVAC Programmer:

The HVAC programmer contains a micro-processor and is the "brain" of the electronic dual zone A/C system. The programmer receives electrical signals from the heater and A/C control, passenger temperature control, right and left solar sensors, outside temperature sensor, inside temperature sensor, blower control module, powertrain control module, drive and passenger air mix valve actuators. A microprocessor in the programmer processes the signals and then sends commands to the system components which control A/C compressor clutch operation, air intake location, air discharge location, air discharge temperature and blower speed.

The solenoid actuated vacuum valves that control air intake and discharge locations are located inside the HVAC programmer. There are four of these valves and each controls vacuum to a different of these solenoid actuated vacuum valves, the HVAC floor outlets, panel outlets, or defroster outlets and whether fresh (outside) air is drawn into the system or inside air is recirculated.

The HVAC programmer also performs self-diagnosis functions for the electronic A/C system. The microprocessor identifies faults when the system is operating and stores this information in memory. When the system diagnostic mode is activated through the use of a scan tool, these faults are displayed as numeric diagnostic trouble codes.