TechChoice Parts carries both new and remanufactured AC Compressors. New AC Compressors are sourced from the highest quality vendors, same as you'd find at most auto parts stores. We remanufacture compressors in-house, and take our time. No quotas, just a policy of building good products every time. We stock A/C Compressors for all makes and models, from Ford, Chevy, Chrysler, and GMC to BMW, Mercedes, and Volvo. Most new compressors, particularly Denso, FS10, and Sanden pumps, come with a full charge of oil, a great value and convenience.

What is an A/C Compressor, and what does it do?

A/C compressor photo

In simple terms, an A/C Compressor is a pump. The compressor is the 'heart' of the air conditioning system, moving refrigerant through the system.

While many people believe the compressor puts out cold air, that is incorrect; it actually creates heat. The compressor puts the air conditioning refrigerant under extremely high pressure. Because pressure and temperature are related, you can see how high pressure refrigerant is actually hot. The cooling is done further down in the system, but we'll get to that later.

The A/C Compressor consists of the compressor itself and the clutch assembly. The compressor has 2 ports, an inlet and outlet, or 'suction' and 'discharge' respectively. The suction port is always the larger diameter hole. Refrigerant is 'sucked' into the compressor, compressed, and 'discharged' through the outlet, headed for the condenser. Inside the compressor is a complex series of passageways, valves, bearings, and other components. There are several types of pumps, including piston type, rotary vane, and scroll.

The compressor clutch is typically a combination of three parts; the hub, pulley, and coil. The hub (sometime referred to as the clutch) is the very front part, a round metal piece. Next is the pulley, which is where the belt rides. Finally, under the pulley is the coil, also called a field coil. The coil contains a tighly wound copper wire, and is essentially an electromagnet. When the A/C is turned on, power is sent to the coil, magnetizing it and, in turn, the pulley. This big magnet pulls the face of the hub onto the face of the pulley. The hub is mated with the shaft of the compressor, which begins rotating the internal parts of the compressor, creating suction and discharge.

The clutch pulley is turning at all times when the engine is on; the belt is turning it. The compressor engages only when the A/C is turned on, and power is sent to the clutch. There are a series of protections built into the A/C system to protect the compressor when certain conditions are not met. If there is not enough refrigerant in the system, a low pressure sensor will keep the compressor clutch from engaging. If pressure is too high, perhaps because of an internal restriction or poor airflow, a high pressure sensor will cut power to the clutch.

Keep in mind, most late model vehicles use the A/C system for Defrost Mode. That's because the air conditioning system is not just for cooling, it's also for dehumidifying.

Below is a diagram of a typical Air Conditioning System. In the center, you can see the A/C compressor.

A/C compressor diagram, showing the location of all the parts and sensors

When the A/C is on, the compressor sucks low pressure refrigerant in, and compresses it to high-pressure, hot refrigerant. The refrigerant travels to the condenser, which is located just in front of the radiator. There the hot refrigerant passes through a series of tubes. Air blowing across the condenser fins cools the refrigerant down. At greater speeds, the air from travel is enough to cool the refrigerant. At lower speeds or when at idle, there are cooling fans or a fan clutch that move air across the condenser. The cooler refrigerant moves from the condenser and heads for the evaporator core. Before reaching the evaporator, the refrigerant must pass through an expansion device, either an orifice tube or expansion valve. The expansion device restricts the flow of the refrigerant, letting it pass through a very small orifice. As the refrigerant passes through this orifice, it expands very quickly, and turns to very cold liquid. A similar effect can be seen when you blow very hard through a straw. The air coming out of the end of the straw is much cooler that the air coming out of your lungs. Put a little water in your mouth and 'mist' it as you blow, and the water will feel pretty cool. Same effect at the expansion device.

The cold refrigerant flows into the evaporator core, which is located in or right at the dash. The blower motor blows air across the evaporator core. As the warm air moves across the evaporator, the heat is removed from it, transferred to the refrigerant, and cold air enters the passenger compartment. Warm refrigerant leaves the evaporator, and heads back towards the A/C Compressor, where the cycle begins again.

The accumulator or receiver drier (accumulators are on the low side, receiver driers on the high side) contain a desiccant bag which filters debris, and act as a reservoir for refrigerant oil. An A/C system will have only an accumulator or receiver drier, not both.

TechChoice Parts stocks thousands of air conditioning A/C Compressors, new and remanufactured, for all types of vehicle. Click below to find your replacement compressor today!

Find your replacement compressor today!