LTD Crown Victoria V8-302 5.0L VIN F FI (1986)
Control Assembly: Description and Operation
Without Air Conditioning
DESCRIPTION AND OPERATION
Heater Control Functions
The manual heater and power ventilation control includes a function control lever for Off, Vent, Floor, Mix, and DEFROST that determines the manner
in which the system will operate. The system has a temperature control lever for manually setting the desired comfort temperature and a blower switch to
control the volume of air movement. Each position of the function control lever and blower switch is detented for positive engagement. The blower
switch provides four manually selected blower speeds and may be operated in any position to select the desired amount of air flow.
Temperature Control
Temperature control of the heater and power ventilation system is determined by the position of the temperature control lever (between COOL and
WARM) of the control assembly and is accomplished by means of a control cable between the control assembly and the temperature blend door.
System air flow is manually controlled by the control assembly. A vacuum selector valve, controlled by the function control lever, distributes
vacuum to the various door vacuum motors which in turn direct the air flow through the system.
The system utilizes what is called a "temperature blend" method to provide controlled temperature to the vehicle interior. With this method all
outside air flow from the blower passes through the heater case to the plenum assembly. Temperature is then regulated by heating a portion of the
outside air and blending it with the remaining cooler outside air to the desired temperature. Temperature blending is varied by the temperature
blend door which controls the amount of air that flows through or around the heater core where it is mixed and directed into the distribution
plenum. The air is finally directed to the heater ducts, the defroster nozzles, or the instrument panel registers according to the selected function
lever position.
System Air Flow
