Heater and A/C Programmer

HVAC Programmer:

DESCRIPTION

The Heating Ventilation and Air Conditioning (HVAC) programmer contains a micro-processor and is the "brain" of the electronic dual zone A/C system.

OPERATION

The programmer receives electrical signals from the heater and A/C control, passenger temperature control, right and left solar sensors, ambient temperature sensor, in-vehicle temperature sensor, blower control module, powertrain control module, driver 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 vacuum actuator. By energizing various combinations of these solenoid actuated vacuum valves, the HVAC programmer can control whether air comes out the 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 TECH 1, these faults are displayed as numeric diagnostic trouble codes.