Control Components

MANUAL A/C
The manual climate control system heats or cools the vehicle interior depending on the position of the function selector switch and the temperature selected. The position of the function selector switch determines heating or cooling and air distribution. The temperature control setting determines air temperature.

The manual climate control system components include:
^ blower motor switch resistor
^ vacuum reservoir tank
^ climate control assembly
^ blower motor relay
^ A/C compressor clutch relay
^ footwell vent vacuum control motor
^ defrost vacuum control motor
^ panel vent vacuum control motor
^ outside air inlet vacuum control motor
^ temperature blend door control cable

Control System Inputs







Climate Control Assembly
The climate control assembly has three system controls:
^ The A/C heater function selector switch combines a vacuum selector valve with two electrical switches to supply battery positive voltage (B+) to the A/C clutch circuit and the blower motor control circuit.
^ The temperature selection is accomplished through cable-controlled positioning of the temperature blend door located in the heater core housing.
^ The blower motor switch controls the blower motor speed by adding or bypassing resistors in the heater blower motor switch resistor.

Control System Outputs







Blower Motor Switch Resistor
The four-speed operation of the blower motor is achieved through the blower motor switch resistor and contains a thermal limiter which is used as a temperature protecting fuse. The assembly is located on the passenger side on the evaporator core housing behind the glove compartment.

Blower Motor Relay
The blower motor relay supplies voltage to the blower motor and is activated when the key is ON and the function selector switch is in any position besides OFF. The blower motor relay is located under the instrument panel next to the steering column.

A/C Compressor Clutch Relay
The A/C compressor clutch relay supplies voltage to the A/C compressor clutch and is located in the Battery Junction Box (BJB). The Power Control Module (PCM) can interrupt the A/C compressor operation through the A/C compressor clutch relay under the following conditions:
^ during engine start-up
^ Wide Open Throttle (WOT)
^ low engine idle conditions
^ excessively high engine temperatures