Fleetwood FWD V8-252 4.1L (1986)
Control Module HVAC: Description and Operation
Power Module
Description
*** UPDATED BY TSB 87-130, DATED JULY 87 ***
Typical Power Module Location Under Hood.
The Power Module controls operation of the blower motor and the A/C compressor clutch. Module control is through the vehicle's computer control
system. For further information, refer to "Computers and Control Systems" or to "Electronic Climate Control".
Operation
Typical Power Module Location Under Hood.
This module controls the operation of the blower motor and is located on top of the evaporator assembly. The power module receives the blower drive
signal from the programmer and amplifies the signal to a strong output signal proportional to the input. The power module is transistorized and provides
variable blower speeds. If the vehicles interior is hotter or colder than the set temperature, the blower will start at high speed and gradually decrease to
low speed as the pre-selected temperature is selected. A heat sink, attached to the power module, protrudes into the evaporator air stream as a means of
dissipating heat which the power module generates. The power module, which receives a signal from the programmer, or BCM (some models), also
cycles the A/C compressor.
The power module incorporates output circuit protection. If the blower motor or clutch coil draws excessive current, the module will turn "OFF" the
output to protect the module and wiring from damage. When the high current condition is corrected, the module will resume normal operation.