The standard PSI (pounds per square inch) for an air conditioner before a gas charge can vary depending on several factors, including the type of refrigerant used, the specific model of the air conditioner, and the ambient temperature. However, I can provide you with some general guidelines.
For most air conditioning systems, the typical operating pressure before a gas charge ranges between 65 to 75 PSI on the low-pressure side (suction line) and 150 to 175 PSI on the high-pressure side (discharge line) when using R-22 refrigerant.
If the air conditioner uses R-410A refrigerant, the typical operating pressure before a gas charge is higher, ranging between 110 to 125 PSI on the low-pressure side and 300 to 350 PSI on the high-pressure side.
Keep in mind that these are general ranges, and it's always best to consult the manufacturer's specifications or the air conditioner's manual for the specific pressure requirements of your particular unit. Additionally, it's important to note that working with refrigerants and air conditioning systems should be done by trained professionals to ensure safety and proper functioning.