General Information

A/C Application Table:

INTRODUCTION
Both the heater and the heater/air conditioning systems share many of the same components. This information will deal with both systems together when component function is common, and separately when they are not.

For proper operation of the instrument panel controls, refer to the Owner's Manual provided with the vehicle.

All vehicles are equipped with a common A/C heater unit housing assembly. When the vehicle has only a heater system, the evaporator and recirculating air door are omitted.

An optional zone control HVAC unit is available. This unit has dual blend-air doors that can be regulated independently of each other. The temperature setting can be different from driver's side to passenger side. There is also a rear (aux.) heating and A/C system available when the vehicle is equipped with zone control.

For proper operation of the rear heating A/C system, refer to Owner's Manual supplied with the vehicle.

SYSTEM OPERATION
Handling Tubing And Fittings
Kinks in the refrigerant tubing or sharp bends in the refrigerant hose lines will greatly reduce the capacity of the entire system. High pressures are produced in the system when it is operating. Extreme care must be exercised to make sure that all connections are pressure tight. Dirt and moisture can enter the system when it is opened for repair or replacement of lines or components. The refrigerant oil will absorb moisture readily out of the air. This moisture will convert into acids within a closed system.

CAUTION:
- The system must be completely empty before opening any fitting or connection in the refrigeration system. Open fittings with caution even after the system has been emptied. If any pressure is noticed as a fitting is loosened, retighten fitting and evacuate the system again.

- A good rule for the flexible hose lines is to keep the radius of all bends at least 10 times the diameter of the hose. Sharper bends will reduce the flow of refrigerant. The flexible hose lines should be routed so they are at least 3 inches (80 mm) from the exhaust manifold. Inspect all flexible hose lines to make sure they are in good condition and properly routed.

- The use of correct wrenches when making connections is very important. Improper wrenches or improper use of wrenches can damage the fittings.

- The internal parts of the A/C system will remain stable as long as moisture-free refrigerant and refrigerant oil is used. Abnormal amounts of dirt, moisture or air can upset the chemical stability. This may cause operational troubles or even serious damage if present in more than very small quantities.

- When opening a refrigeration system, have everything you will need to repair the system ready. This will minimize the amount of time the system must be opened. Cap or plug all lines and fittings as soon as they are opened. This will help prevent the entrance of dirt and moisture. All new lines and components should be capped or sealed until they are ready to be used.

- All tools, including the refrigerant dispensing manifold, the manifold gauge set, and test hoses should be kept clean and dry.

System Airflow
The system pulls outside (ambient) air through the cowl opening at the base of the windshield. Then it goes into the plenum chamber above the heater-A/C unit housing. On air conditioned vehicles, the air passes through the evaporator. At this point the air flow can be directed either through or around the heater core. This is done by adjusting the blend- air door with the TEMP control on the control head. An optional zone control HVAC control module is available. This unit has dual blend-air doors that can be regulated independently of each other. The temperature setting can be different from driver's side to passenger side. After the air passes the blend-air door(s), the air flow can then be directed from the Panel, Floor, and Defrost outlets. Air flow velocity can be adjusted with the blower speed selector switch on the control head.

Ambient air intake can be shut off by closing the recirculating air door. This will recirculate the air that is already inside the vehicle. This is done by depressing the Recirc. button on the control head. On air conditioned vehicles, moving the control to Mix or Defrost depresses the A/C button and will engage the compressor. This will send refrigerant through the evaporator, and remove heat and humidity from the air before it goes through the heater core.

CAUTION: In cold weather, use of the Recirculation mode may lead to excessive window fogging. The Recirculation mode is automatically deactivated in Mix and Defrost modes to improve window clearing operation.

System Oil Level
It is important to have the correct amount of oil in the A/C system to ensure proper lubrication of the compressor. Too little oil will result in damage to the compressor. Too much oil will reduce the cooling capacity of the system and consequently result in higher discharge air temperatures.

NOTE: The oil used in the compressor is ND8 PAG R134a refrigerant oil. Only refrigerant oil of the same type should be used to service the system. Do not use any other oil. The oil container should be kept tightly capped until it is ready for use. Tightly cap afterwards to prevent contamination from dirt and moisture. Refrigerant oil will quickly absorb any moisture it comes in contact with. Special effort must be used to keep all R-134a system components moisture-free. Moisture in the oil is very difficult to remove and will cause a reliability problem with the compressor.

It will not be necessary to check oil level in the compressor or to add oil unless there has been an oil loss. Oil loss at a leak point will be evident by the presence of a wet, shiny surface around the leak.

Rear Heater And A/C Lines

Rear Heater And A/C Lines:

Front Lines Connected To Rear Lines:

Rear Heater Hose Connection:

Rear Heater Hose Quick Connects:

Rear A/C Block Connection:

The rear heater and A/C lines are all serviced as individual pieces. when disconnecting any line or block ensure that the area around it is clean of any contaminations that can get in to the system.

A/C Control Panel:

Rear Blower Switch:

The auxiliary rear heating-air/conditioning unit is located in the right rear quarter panel. The rear heater A/C control operates in conjunction with the front heater A/C control. A four position two speed blower (override) switch is located on the front Heater A/C control panel. The operator can use the rear heater A/C blower switch to operate the blower, regardless of the rear control setting. In the OFF position, the rear control will not function. In the ON (RR) position, the rear control will function normally providing three speeds. The mode setting is controlled by the front A/C control panel.

Air from inside the vehicle is drawn into the air intake grille in the right rear quarter trim panel. The air enters the blower and is pushed through the heater core and A/C evaporator coil. The air direction, floor or overhead, is determined by the position of the driver's temperature control lever on the front HVAC system control. If the temperature control lever is below 20% heat, the auxiliary HVAC system airflow will come from the overhead air outlets. In between 20% and 80%, the airflow will remain in the last position selected. In other words, if the driver started out in full heat and then adjusted their temperature lever to 30% heat as they became comfortable, the rear air would come out the floor outlets the whole time.