For 1990-2009 cars

### V5 and SP10 Compressor - General Description

Different vehicles with V5 and SP10 compressors may exhibit differences in mounting and installation, but overhaul procedures are similar.

Before removing the compressor or performing on-vehicle repairs, clean the compressor connections and the outside of the compressor.

Important: After removing a compressor from the vehicle for servicing, drain the oil by removing the oil drain plug. Also drain the oil from the suction and the discharge ports to insure complete draining. Measure the amount of oil drained, and record that amount. Discard the used oil and add the same amount of new polyalkylene glycol (PAG) refrigerant oil to the compressor.

The compressor has been removed from the vehicle unless otherwise indicated.

Clean tools and a clean work area are important for proper servicing. Keep dirt and foreign material from getting on or into the compressor parts. Parts that are to be reassembled should be cleaned with trichloroethane, naphtha, stoddard solvent, kerosene, or equivalent solvents. Dry the cleaned parts with clean dry air. Use only lint-free cloths to wipe the parts.

### V5 Compressor - Description of Operation

The V5 is a variable displacement compressor that can match the automotive air conditioning (A/C) demand under all conditions without cycling. The basic compressor mechanism is a variable angle wobble-plate with 5 axially oriented cylinders. The center of control of the compressor displacement is a bellows-actuated control valve located in the rear head of the compressor. The control valve senses compressor suction pressure.

The wobble-plate angle and the compressor displacement are controlled by the crankcase suction pressure differential. When the A/C capacity demand is high, the suction pressure will be above the control point. The valve will maintain a bleed from crankcase to suction. With no crankcase suction pressure differential, the compressor will have maximum displacement.

When the A/C capacity demand is lower and the suction pressure reaches the control point, the valve will bleed discharge gas into the crankcase and close off a passage from the crankcase to the suction plenum. The angle of the wobble-plate is controlled by a force balance on the 5 pistons. A slight elevation of the crankcase suction pressure differential creates total force on the pistons resulting in a movement about the wobble-plate pivot pin that reduces the plate angle.

The compressor has a unique lubrication system. The crankcase suction bleed is routed through the rotating wobble-plate for lubrication of the wobble-plate bearing. The rotation acts as an oil separator which removes some of the oil from the crankcase suction bleed, re-routing it to the crankcase where it can lubricate the compressor mechanism.

### SP10 Compressor (1.2L Engine) - Description of Operation

The SP10 is a fixed 110-cc displacement swash plate compressor. It consists of 5 double-ended pistons reciprocated in 10 cylinder bores by the swash plate and shaft assembly. There are 10 hemispheric shoes connecting the pistons to the swash plate and shaft assembly. As the swash rotates, the shoes swivel. Thus the rotary motion of the swash plate is converted to the reciprocating motion of the pistons.

### Condenser Core

The condenser assembly in front of the radiator consists of coils which carry the refrigerant and cooling fins that provide the rapid transfer of heat. The air passing through the condenser cools the high-pressure refrigerant vapor and causes it to condense into a liquid.

### Expansion Valve

The expansion valve is located on the passenger compartment side of the dash panel, near the right front strut tower. The expansion valve can fail in 3 different positions: open, closed, or restricted.

An expansion valve that fails in the open position will result in a noisy A/C compressor or no cooling. The cause can be a broken spring, a broken ball, or excessive moisture in the A/C system. If the spring or the ball are found to be defective, replace the expansion valve. If excessive moisture is found in the A/C system, recycle the refrigerant.

An expansion valve that fails in the closed position will result in low suction pressure and no cooling. This may be caused by a failed power dome or excessive moisture in the A/C system. If the power dome on the expansion valve is found to be defective, replace the expansion valve. If excessive moisture is found in the A/C system, recycle the refrigerant.

A restricted expansion valve will result in low suction pressure and no cooling. This may be caused by debris in the refrigerant system. If debris is believed to be the cause, recycle the refrigerant, replace the expansion valve, and replace the receiver-dryer.

### Evaporator Core

The evaporator is a device which cools and dehumidifies the air before it enters the vehicle. High-pressure liquid refrigerant flows through the expansion tube (orifice) and becomes a low-pressure gas in the evaporator. The heat in the air passing through the evaporator core is transferred to the cooler surface of the core, which cools the air. As the process of heat transfer from the air to the evaporator core surface is taking place, any moisture in the air condenses on the outside surface of the evaporator core and is drained off as water.

### Receiver-Dryer

The receiver-dryer acts as a refrigerant storing container, receiving liquid and some vapor and refrigerant oil from the evaporator.

At the bottom of the receiver-dryer is the desiccant, which acts as a drying agent for the moisture that may have entered the system. An oil bleed hole is located near the bottom of the receiver-dryer outlet pipe to provide an oil return path to the compressor. The receiver-dryer is serviceable only as an assembly with the condenser.

### Heater Core

The heater core heats the air before it enters the vehicle. Engine coolant is circulated through the core to heat the outside air passing over the fins of the core. The core is functional at all times and may be used to temper conditioned air in the A/C mode as well as in the heat or the vent mode.

### Evaporator Thermistor (1.2L SOHC/DOHC SP10 A/C System Only)

A thermistor is a sensor which detects the temperature of refrigerant in the evaporator. If the temperature of an evaporator drops to 0°C (32°F) or below, the evaporator core gets stuck with frost or ice, resulting in reduced airflow and impaired cooling capability.

To prevent this, the engine control module (ECM) monitors the temperature signal from the thermistor and controls the operation of the compressor. If the temperature of the evaporator drops to 2°C (35.6°F), the compressor clutch is disengaged until the temperature goes over 4°C (39.2°F).

The thermistor is located in the evaporator.