If the compressor is tested or know to be bad, you need to pull the system down, suck out all of the refrigerant, and then remove the compressor and reinstall the new, using a new gasket/o-ring on the fittings.
You can use a used compressor, I have one on my car from ED cause my compressor was leaking oil out, and was cheaper to replace the compressor than rebuild/reseal mine.
Its always good practice to replace the receiver dryer and the orifice tube when ever your replacing the compressor. The receiver dryer is easy to do, the orifice tube is kinda a PITA to do, but really needs to be done as this is really a filter for the system, and when clogged...can cause many problems.
The orifice tube is located on the drivers side, in line with the receiver dryer, tucked back along the side of the strut tower, under the master cylinder. The replacement part goes INSIDE the fitting, when the line is unscrewed and opened up. You simply pull out the old, and install the new. Easy to replace, just sucks getting to it to do.
Might check the system and make sure its not low on refrigerant, or, check your fuses, and relays and make sure none of those are bad or blown as well before you go though with it all.
~F~
