How does a vehicle's air conditioning work?

How a vehicle's air conditioning system functions:

What it does not do:

Cold air is not created by the vehicle’s air conditioning system. It actually takes heat and moisture out of the air that is already in a vehicle!

The process:

A vehicle's air conditioning is pressurized by a gas called a refrigerant. The air conditioning compressor compresses the refrigerant from a gas to a fluid and the fluid is cycled through the refrigerant line. As fluid travels through the high-pressure lines to the condenser, the condenser which is similar to a small radiator puts the liquid in contact with fresh air on the outside of the vehicle, which absorbs the heat from the liquid. It then flows into the expansion valve where it is restricted and becomes a gas again. 

The gas then flows into the accumulator. The air conditioner accumulator is a metal canister that acts as a filter for the air conditioning system. It contains a desiccant bag to remove and collect unwanted moisture/water and impurities. To optimize the operation of your vehicle's precious air-conditioning system, the accumulator needs to have a reliable A/C Desiccant BagDesiccants are substances that dry off the refrigerant before it cycles back into your system, allowing it to exchange heat more efficiently. The refrigerant in a gas format then travels through the tubing into the evaporator(that is usually located in the passenger compartment, absorbing heat from the air passing through the evaporator fins, leaving behind the cooler air. Fans blow this cooler dry air into the compartment. The refrigerant travels back to the compressor in the suction hose of the a/c system to get compressed back into the high-pressure gas and begin the process again.

Troubleshooting: If the refrigerant level gets low, the a/c system can still operate, even though it may lose some of its cooling effects. It may also shorten the cycle of operation, and it can cause damage due to the compressor not being properly lubricated while operating.


  • Any obvious leaks. If the refrigerant level is low, it is due to a leak that has developed in the system.
  • Pressures of the air conditioning system while in operation can give an indication of low refrigerant, but it cannot tell how low the level is. 
  • The operation of the compressor, it’s clutch and belt, check the high and low pressures of the system while in operation.
  • Proper control panel operation.
  • Heater blower fan and engine cooling fan operation.
  • Restrictions in the system and proper airflow through the condenser and evaporator.


Posted on Sep 21, 2020 by Auto Repair Directory

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