GMC Repair: A/C, correct oil, orifice tube

Question
What is the correct replacement a/c compressor and clutch for a 1991, Chevy 2500, Ext. cab, 454 size engine.  Do I need to replace the accummulator?  What are the refrigerants I need?

Thank you -
Louis

Answer
Hi Louis. There is a number on your AC compressor, your parts supplier will get you the correct one by matching the number. You should replace the receiver drier and also the orifice tube. check the decal under your hood for the correct freon and amount, do not add more than specified. You will also need the correct oil for your freon type, do not try to interchange freons and oils. AC should be done by trained techs, the system is under preasure and equipment is needed to do the job properly, all moisture must be vacuumed from the system, moisture is the worst thing for AC systems. I would recommend a minmum of 3 hours of evacuation and more if time allows, even overnight won't hurt. Good luck and if you are going to do this yourself, get help from a knowlegable AC tech. MANFRED