AC Compressor

What is an AC Compressor and what does it do?

The AC compressor is responsible for pumping refrigerant throughout your system and starting the process of cooling your car. Without it, your vehicle's AC system won’t work and you may experience a lack of cold air coming through your vents.

The compressor has two ports, a suction inlet and a discharge outlet. Refrigerant enters through the inlet and is compressed under extremely high pressure before exiting the outlet and being routed to the condenser and the system at large. The travel of refrigerant through your vehicle is called the refrigeration cycle, and it starts and begins at the compressor.

How to tell if your AC Compressor is bad?

Bad AC compressor symptoms include a hot cabin, a non-moving clutch, refrigerant leaking, and loud squealing or grinding when the compressor is on.Any of these symptoms can indicate a compressor that has stopped working, although in some cases, you may just need to add AC compressor oil.

How does an AC Compressor work?

The AC compressor is powered by a drive belt that connects to the engine’s crankshaft. The belt is connected to the compressor clutch pulley. While the clutch pulley turns whenever the engine is on, the compressor only activates when air conditioning (and in some cases defrost) is in use. That’s because the clutch pulley is connected to a field coil which can be magnetized with electric current. Magnetism attracts the hub and shaft to the pulley, allowing the clutch to turn the compressor.

It might seem counterintuitive, but the compressor heats up refrigerant before cooling it down. Increased pressure causes the refrigerant to get very hot. Because the refrigerant is pressurized, it is able to expand, allowing the compressor to effectively pump the refrigerant into a high-pressure line that runs to the condenser. This quick release begins the cooling of the gas, which continues in the condenser fan where air that flows across the lines helps cool it even more.

The gas eventually reaches the evaporator, where refrigerant vaporizes to absorb heat from the cabin air, leaving you with cool air. At this point the refrigerant can travel up the low-pressure line back to the compressor, where the cycle begins again. This cycle runs continuously when AC is on to cool your vehicle’s cabin air.