That depends on what kind of AC system it is (e.g., home, commercial, automotive) and when it was manufactured.
r134 a r134 a
r134a
R134a
Refrigerant is commonly added in the outside ac unit. The freon is filled through the low side ac port.
A 1998 Buick would use R134a refrigerant.
Any auto parts store will carry an AC recharge kit. You should buy the refrigerant R-134a, and a hose that will connect to the AC line on your engine and to the AC can of refrigerant. It is best to buy the hose with a pressure gauge so you do not overfill the refrigerant. In your engine compartment there is a silver tube that runs from the AC compressor to the firewall. There will be a blue cap on the hose that has a L or says LOW. This is the low side and you MUST put the refrigerant in this line. Hook up the AC can to the LOW line and start your engine with the AC on full blast. Check the pressure gauge and if it is low open the valve to add AC refrigerant. Fill until the can is empty or the gauge says it is full. Enjoy
Low refrigerant charge?
possible low refrigerant
low refrigerant charge or restriction of airflow
r134a
the kind that it takes
You are low on refrigerant, google R134a...