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How to Add Freon to a 1999 Pontiac Grand Am

by Kyle Sanstrom

The pressure in the air conditioning system on a 1999 Pontiac Grand Am must be between 25 and 45 psi. When the pressure falls below 25 psi, the system will not produce sufficiently cool air. If the pressure is greater than 45 psi, damage to the system can occur. The air conditioning system requires R-134a refrigerant; this refrigerant must be added periodically in order to maintain the proper pressure level. R-134a refrigerant is available at most auto parts or home and garden stores.


Drive the vehicle until the engine reaches operating temperature. Place the transmission in "Park" and allow the engine to idle.


Apply the parking brake and open the hood. Turn the air conditioning selector knob to “Max A/C” and place the blower fan on its highest setting.


Locate the blue low-pressure port cap and remove it (you will find it attached to the low-pressure port fitting, on top of the large diameter aluminum refrigerant line located to the left of the air conditioning compressor).


Connect one end of the in-line refrigerant pressure gauge to the low pressure port. Connect the other end to the refrigerant canister.


Record the reading on the pressure gauge.


Rotate the refrigerant canister until it is upside-down. Gradually tighten the refrigerant release valve until it punctures the seal on the R-134a refrigerant canister. Monitor the pressure gauge. Loosen the release valve to stop the flow of refrigerant once the pressure gauge displays a reading of 45 psi.


Remove the pressure gauge and replace the low-pressure port cap. Check the temperature of the air inside the vehicle to make sure it is sufficiently cool.

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About the Author

Kyle Sanstrom has been writing professionally since 2008. His articles have been published on several websites including eHow and Automobile Insight. Sanstrom has undergone advanced automotive training at the Dunwoody College of Technology, holds an Associate of Arts in general studies from Century College and has more than 10 years of experience in all aspects of automotive repair and diagnosis.

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