How Your Car’s A/C Works

Your air conditioning system primarily works through cycling refrigerant through high and low pressure, utilizing the rapid cooling that happens when it expands from a liquid to a gas form.

As the refrigerant goes from high pressure to low, there are several stages of increasing or decreasing pressure. Most cars’ air conditioning systems are made of these parts:

  • Compressor: The compressor takes the refrigerant when it’s in a gas form and pressurizes it, and pumps it through the system. Powered by the serpentine belt, the compressor is the core component of any cooling system.
  • Condenser: From the compressor, gaseous refrigerant moves to the condenser, which transforms it from gas to liquid form. The condenser looks very much like a radiator and can produce a lot of heat as it removes it from the high-pressure refrigerant.
  • Receiver-Drier: The receiver filters the now-liquid, highly-pressurized refrigerant in order to remove debris or water. These extra elements can damage the air conditioning system.
  • Thermal Expansion Valve OR Orifice Tube: Most cars’ A/C systems are similar, however the one place that they might differ is whether they use an orifice tube or a thermal expansion valve. In either case, both of these devices have the same job: to monitor the flow of refrigerant and relieve pressure so that the refrigerant can expand into gas form.
  • Evaporator: The evaporator is there for the beautiful moment when the liquid refrigerant rapidly expands, quickly cooling the air. Usually, the evaporator is located right behind your dash, equipped with fins and pipes that also make it look a bit radiator-ish. A blower fan pushes air over the evaporator and straight into your car’s cabin.

From there, the refrigerant is again drawn into the compressor in order to cycle through the system, again and again, providing you with deliciously cool air.


Look to Master AutoTech for all things air conditioning.

Understanding Refrigerant

Refrigerant is used because it evaporates at a low temperature, and condenses at a higher temperature. Refrigerant is any element that can be boiled into a vapor and then compressed into a liquid. This means that even water is a refrigerant (and indeed, we take advantage of its cooling properties all the time.) However, other elements that are used specifically for refrigerant have a lower boiling point (or temperature at which they evaporate) and condense at a higher temperature. This gives us a faster cooling effect which gives us the chill of an air conditioner.

Almost all air conditioners today use a freon refrigerant called R-1234YF, which replaced the old R-134A because it runs cleaner and more efficiently.

Maintaining Your Air Conditioning System

Many professionals recommend having your A/C checked every year. An A/C checkup can ensure the efficiency of your car, since running the air conditioner does take energy from the engine and cost you extra gas. Yearly checks can identify leaks early, which makes them easier and cheaper to fix, and can prevent one broken part from compromising the whole air conditioning system.

Come by any of our Master AutoTech locations today. We can give your air conditioning system a checkup and if we detect any problems, we can get your system back to top function in time for your summer.

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