I'm pretty sure my compressor is shot but I wanted to double check. For the last month or so I started using the AC, it was cool, but not nearly as good as it was last year. Figured it needed a recharge, so I picked up a can and went to recharge it. No good. Low side pressure was high, about 90psi. At first I thought there was moisture in the system. So I had it evac'ed and refilled. Still nothing. Low side pressure is 70ish psi, high side is 110psi. Compressor still spins fine, but when it kicks on, there isn't much change in the gauges.

So, compressor is shot I am guessing?

If so, I am going to replace the orifice tube as well, do I need anything special to replace that?

I am doing the waterpump and tensioner as well, so I figure pulling the compressor shouldn't be difficult, if I can find one in stock around me.

 

i would say your right on the bad compressor if there is little to no change in pressure when engaged unless you got some blockage in the orifice .While you have the system open and the piston out blow some compressed air through the system to make sure its clear before all the new stuff is installed.goodluck

 

Just remembered, anyone know how much oil I need to put back in the system?

 

Id do the accumulator as well to help get any moisture out of the system. Oil capacity is usually 6-8 oz total but you wont get all of that out without some specialized equipment add a couple oz to the compressor before you replace it. Most of the original oil will fall out of suspension with the freon and remain in the system

 

you would be correct in assuming the compressor needs replacement.
when it was evac'd did anyone pull the orifice tube and check?
with around 100 psi static pressure with the ac off (depending on engine bay temperature) when the ac clutch engages and compressor starts spinning if the low side doesn't drop down below 50 psi quickly then the compressor is shot.
removing the compressor is not hard and you could easily do that yourself. however the work involved to service the AC system properly is most likely beyond your means. given that your compressor is shot, you don't know how bad until you remove it and inspect it and the lines for metal debris and black sludge oil. if either is the case then you need to completely flush the ac system to clean it out otherwise any crap will destroy the new compressor, and new compressor warranty for it to be honored requires this complete servicing of the system and usually by a licensed AC repair shop, otherwise you will have to somehow prove you yourself did. you can't just blow things out with compressed air. given the age of the car, you'll definitely need a new accumulator, and depending on how bad the compressor puked debris into the system an evaporator flush- potentially new AC lines if you suspect any to have a leak otherwise a flush of those, and if debris in the system a new condenser in front of the radiator because those cannot be flushed reliably. the orifice tube is the only thing you can reuse, that's just a piece with a hole in it that you can remove and easily clean.
so once you have the evap and anything else properly flushed with AC flush solvent you can easily install everything and close up the system. after that it's a matter of purging it and pressure testing with nitrogen if available, then pulling a deep vacuum to evacuate all moisture. then you inject oil and charge with r134a.
total system capacity is 9 ounces PAG oil and 1.5 lbs r134a.
the viscosity of pag oil is dependent on the compressor, but i believe all gm vehicles use PAG-150. don't use synthetic ester type oils.
a new compressor may come shipped with or without oil, if it has oil you drain it out then inject the correct amount of oil into the system (9 oz) if everything else has been replaced and flushed. replace all your o-rings on line fittings and use mineral oil (not pag oil) meant for ac system o-rings, and replace your high and low service port valves and o-rings.