System Components

V-5 Compressor:

Expansion Tube:

REFRIGERANT-134a

The air conditioning system contains Refrigerant-134a, which requires special handling to avoid personal injury. Refer to "Handling Refrigerant".

COMPRESSOR

The V-5 compressor is driven by a belt from the engine crankshaft through the compressor clutch pulley. The compressor pulley rotates freely, without turning the compressor shaft, until an electromagnetic clutch coil is energized. When voltage is applied to energize the clutch coil, a clutch plate and hub assembly is drawn rearward toward the pulley. The magnetic force locks the clutch plate and pulley together as one unit to drive the compressor shaft. Compressor engagement is automatic in "MAX" and "DEFROST" modes. In all other modes, the "A/C" switch must be on to engage the compressor.

As the compressor shaft turns, the compressor performs two main functions. It compresses the low-pressure refrigerant vapor from the evaporator into a high-pressure, high-temperature vapor. It also pumps refrigerant (and refrigerant oil) through the A/C system.

PRESSURE RELIEF VALVE

The compressor is equipped with a pressure relief valve which is placed in the system as a safety factor. Under certain conditions, the refrigerant on the discharge side may exceed the designed operating pressure. To prevent system damage, the valve is designed to open automatically when high side pressure exceeds a specified amount. Conditions that might cause this valve to open (defective A/C pressure sensor, inoperative electric cooling fan, etc.) should be corrected, and the refrigerant oil and refrigerant should be replaced as necessary.

CONDENSER

The condenser in front of the radiator is made up of coils which carry the refrigerant. Cooling fins provide rapid transfer of heat. Air passing through the condenser cools the high-pressure, high-temperature refrigerant vapor, causing it to condense into a liquid.

COOLANT FAN

The coolant fan operation is crucial to the proper operation of the A/C system. The coolant fan ensures the proper amount of air flow across the condenser throughout the vehicle's operating range.
The fan operation should be checked during any A/C diagnosis procedure. Special attention should be given to the fan whenever excessive high-side pressures are encountered, the high pressure relief valve discharges, or if the A/C pressure sensor opens. The coolant fan is mounted to the rear of the radiator.

Coolant fan control circuits vary with carline and engine application.

EXPANSION TUBE

The expansion tube is a plastic assembly containing a fixed diameter tube with a mesh filter screen at either end. It is located at the condenser outlet tube. The fixed diameter tube creates a restriction to the high-pressure liquid refrigerant in the liquid line, metering the flow of refrigerant to the evaporator as a low-pressure liquid. When the engine is turned "OFF" with the A/C system operating, the refrigerant in the system will flow from the high-pressure side of the expansion tube (orifice) to the low-pressure side until the pressure is equalized. This may be detected as a faint sound of liquid flowing (hissing) for 30 to 60 seconds and is a normal condition.

When system diagnostics indicate a restricted expansion tube, it may not be necessary to replace it. Metal chips, flakes or slivers found on the screen may be removed with compressed air and the expansion tube may be reused if:

- The plastic frame is not broken.
- The brass expansion tube is not damaged or plugged.
- The screen material is not torn.
- The screen is not plugged with fine gritty material.

EVAPORATOR

The evaporator is a device which cools and dehumidifies the air before it enters the passenger compartment. High-pressure liquid refrigerant flows through the expansion tube, becomes a low-pressure liquid, and then enters the evaporator. The heat in the air passing through the evaporator core is transferred to the cooler surface of the core, thereby cooling the air. As the process of heat transfer from the air to the evaporator core surface is taking place, any moisture (humidity) in the air condenses on the outside surface of the evaporator core and is drained off as water. The evaporator is located inside the HVAC module at the front of dash.

ACCUMULATOR

Downstream of the evaporator outlet pipe, the sealed accumulator assembly functions as a liquid/vapor separator. It receives refrigerant vapor, along with some liquid refrigerant and refrigerant oil from the evaporator. It allows only refrigerant vapor and oil to pass on to the compressor.

At the bottom of the accumulator is the desiccant bag. It acts as a drying agent for moisture that may have entered the system. An oil bleed hole is located near the bottom of the accumulator outlet pipe to provide an oil return path to the compressor.

If the system is open to air for an extended period of time (due to a front-end collision, removed parts, etc.) replace the accumulator. The desiccant bag will be saturated with moisture. The accumulator is serviced by replacement only. The accumulator is located in the right hand corner of the engine compartment and is attached to the front of dash.