Fleetwood FWD V8-252 4.1L (1986)
Control Module HVAC: Description and Operation
Programmer Assembly
The programmer is located in the passenger compartment on the right end of the heater and A/C assembly on Deville and Fleetwood or attached to the
HVAC module assembly behind glove box on Eldorado & Seville.
The circuit board mounted in the plastic case accepts coded data signals from the BCM and processes these to provide output control signals. The board
controls the DC motor drive signal which adjusts air mix door position and the vacuum solenoid drive signals which provides vacuum to various
actuators. The programmer also transmits the A/C compressor clutch drive signal to the power module on all models and the blower drive signal on
Eldorado and Seville models. On all models the programmer provides a ground signal for the rear defogger relay (if equipped).
The DC motor is located inside the plastic programmer case and actuates the rotary shaft that drives the air mix door link. The DC motor is reversible
and provides a potentiometer feedback signal that is used by the BCM to determine air mix door position.
Four vacuum solenoids mounted within the plastic programmer case are actuated by signals within the circuit board. These solenoids control vacuum to
actuators that open or close the heater water valve, air inlet door, up-down door and A/C-DEF door.
