How to Add the Proper Amount of Freon

by Alexander Poirier

When a car's air conditioning system does not have the right amount of freon, the performance of the unit is compromised. Too much or too little freon can result in air that is not as cool as it should be. Air conditioner recharge kits come with gauges to read the pressure of the freon in the air conditioning unit. By adding freon until these gauges read the proper PSI, you can ensure that your air conditioner is running at peak performance.

Open the vehicle's hood and locate the air conditioner's high pressure and low pressure service ports. See the owner's manual for their exact location.

Start your vehicle and turn the air conditioner on at its maximum settings. Let the car idle for at least five minutes.

Attach the low pressure gauge hose that came with the recharge kit to the low pressure service port. Attach the high pressure gauge hose to the high pressure service port.

Read the gauges with the air conditioner on maximum settings. The low pressure gauge should read anywhere between 20 to 35 PSI and the high pressure gauge should read between 200 and 350 PSI. If both sides are lower than these readings, the vehicle needs freon. If both gauges read higher than normal, the vehicle has too much freon.

Attach the can of freon to the low pressure gauge hose. Twist the valve on top of the can to puncture the can and begin the filling process. Twist the valve in the opposite direction to stop the filling process once the low pressure gauge reads between 20 and 35 PSI.


  • check Draining freon from a vehicle should only be performed by an experience auto mechanic. Do not attempt this process by yourself.

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About the Author

Alexander Poirier began writing professionally in 2005. He worked as the editor-in-chief of the literary magazine "Calliope," garnering the magazine two APEX Awards for excellence in publication. Poirer graduated from the University of the Pacific with a Bachelor of Arts in English.

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