Underneath the car. no need to jack the car up. its a blue valve
R134a
Low pressure port.
A 1998 Buick would use R134a refrigerant.
Originally R-12 - should be converted to R134A
It came with R12 Freon. As R12 is cost prohibitive, have the unit converted to R134a refrigerant or a similar substitute.
Connect a freon gauge and tank to the low side ac port. Start the engine and turn ac on high. Open the valve and let the freon flow until the system shows full.
Remove the freon from the system. Disconnect the compressor belt, then remove the lines. Unbolt the compressor and remove it. Install the new compressor, connect the lines and belt. Pull a system vacuum, then fill with new freon.
Your car uses 134 refrigerant. But a kit at most auto stores, etc. The kits have easy instructions to follow better than can be explained here.
A 1994 Buick Regal Custom uses 134a refrigerant, not freon.
Underneath near radiator. There is a nipple with a black plastic cover. I recommend accessing this from under the vehicle if hot. The exhaust manifold could cause burns if accessed from above.
remove it carefully... pull the bolts... do not cut any freon lines... that's illegal in the epa's book.... i personally havent read it... if you should accidently cut any lines.. don't inhale the freon... it could really mess up our lungs
Your A/C system may be leaking, which would mean that it will not hold a charge of freon, as thusly will not cool.