How to Check the AC on a Car

by Tatyana Ivanov

Car air conditioner systems have multiple parts and if any of them malfunction your air conditioner may stop working properly. If you find your car's air conditioning system is not producing the cool air it used to, there are a number of simple ways to investigate the cause of the problem. Most air conditioner malfunctions occur due to a lack of refrigerant, sometimes caused by leaks in the air conditioning unit.

Check the Refrigerant Level

Turn off your car, then open the hood and locate your air conditioning unit. Air conditioning units are located at various places depending on the type of car you own. If you have trouble finding it, consult your car manual. The unit will have a compartment for the refrigerant and a fan system.

Connect the AC pressure gauge to the side port of the air conditioning unit. Turn on the car and allow the engine to run for a few minutes.

Depress the accelerator. If the AC pressure gauge's meter dips down when you accelerate, there is not enough refrigerant in the vehicle.

Check for Leaks

Visually inspect the air conditioning unit with your car running. Check to see if the compressor is cycling and if the fan belt seems work.

Inject a small amount of auto-safe florescent dye into the air conditioning unit. This florescent dye is available at most auto parts stores and allows you to see any leaks or damage in the air conditioner unit. Follow the directions for insertion on the can.

Visually inspect the air conditioner unit for any holes or leaks in the pipes, tubes or compressors. The florescent dye will cover any holes or cracks, making them easy to spot.

Fix cracks or holes before adding more refrigerant to prevent pollution and damage to your vehicle.


  • close Do not poke or insert anything into the air conditioner unit. This may cause a dangerous leak and is illegal under federal law.

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About the Author

Tatyana Ivanov has been a freelance writer since 2008 and has contributed articles to "Venus" and "Columbus Family." She continues to write humor pieces for a number of popular culture blogs. Ivanov holds a Bachelor of Arts in media studies from Hunter College.