Bonneville V6-3800 3.8L VIN L SFI (1995)
Control Module HVAC: Description and Operation
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.
