General Description

The air conditioning system delivers air that has been heated or cooled and dehumidified for occupant comfort. It also provides ram air, power ventilation, windshield defrosting, and side window defogging.

During most operating conditions, fresh outside air is drawn into the ventilation ducts by the blower. Additional outside air (ram air) is also forced into the vehicle by forward movement of the vehicle.

Within the ventilation ducts, the air is pushed by the blower motor through the evaporator, then through the heater core, and into the passenger compartment. For air conditioning or defroster operating modes, the refrigeration system will chill the evaporator to almost freezing. As the air passes through the evaporator, the air temperature drops which causes moisture in the air to condense on the evaporator core tins. This moisture leaves the vehicle by gravity feed through a drain hole, dehumidifying the vehicle.

From the evaporator case, some or all of the air may pass through the heater core, which is warmed by engine coolant. Any of the air which is not to be heated will mix with the heated air before entering the passenger compartment.

For maximum air conditioning, set the fresh/recirc control lever to recirculation. This way, most of the air entering the blower during this mode is taken from the passenger compartment (recirculated) where the air is likely to be cooler than outside air.

For heater-only or ventilation modes, the A/C system can shut off so cooling is not provided. The operator can turn off the A/C system by setting the A/C switch to off. The amount of heating is governed by the proportions of the air directed through or around the heater core in the same manner as with air conditioning. The heater control unit assembly in the instrument panel gives the operator a means of selecting the desired operating mode, air temperature and blower speed when the engine is running.

Important
^ Before any work is performed on the air conditioning system, review precautions on handling Refrigerant-134a (R-134a) along with the discharging, recovery and recycling procedures.