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.