Air conditioning (Distribution system): Description and operation

The rear evaporator/blower assembly cools and dehumidifies air from the cabin and supplies it to the rear distribution system. The unit is installed on the left side of the loadspace, behind the quarter trim. A grille in the quarter trim allows air to flow from the loadspace into the evaporator/blower. Refrigerant lines for the evaporator and a condensate drain tube are attached to the rear floor.

The evaporator and blower are installed in a common housing, which also incorporates the resistor pack for the blower. A thermostatic expansion valve is integrated into the inlet refrigerant line. A rear blower relay is attached to the top of the housing.

Evaporator The evaporator absorbs heat from the recirculated air being supplied to the distribution ducts.

Thermostatic expansion valve The thermostatic expansion valve meters the flow of refrigerant into the evaporator to match the heat load of the air passing through the evaporator matrix. A capillary tube, attached to the outlet pipe of the evaporator and connected to the thermostatic expansion valve, automatically adjusts the valve opening in relation to the refrigerant temperature at the evaporator outlet.

Blower The blower controls the volume of air being supplied to the distribution outlets. The blower is an open hub, centrifugal fan powered by an electric motor. A dust filter is installed over the fan inlet. The blower switch on the control panel and the resistor pack control the operation of the blower, which can be selected to run at one of four speeds.

Resistor pack The resistor pack supplies reduced voltages to the blower motor for blower speeds 1, 2 and 3. For blower speed 4, the resistor pack is bypassed and battery voltage drives the motor at full speed. The pack is installed in the air outlet from the blower fan, so that any heat generated is dissipated by the air flow.

Distribution system

Air ducts Ducts connected to the rear evaporator/blower motor assembly distribute air to five vent assemblies in the roof.

Vent assemblies The vent assemblies allow occupants to control the flow and direction of air. Each vent assembly incorporates a thumbwheel to regulate flow and moveable vanes to control direction.

Rear control system

The control system operates the blower to control the operation of the rear A/C. The control system consists of two control switches and a rear blower relay.

Control switches A rear A/C switch and a blower speed switch are installed on a control panel in the roof lining. The A/C switch is a latching pushswitch with an amber indicator lamp which illuminates when rear A/C is selected on. The blower speed switch is a slide switch with a positive detent at each of four speed positions (there is no off position).

Rear blower relay The rear blower relay controls the electrical supply to the blower.