99 Venture, AC Not Cool

My AC went out last weekend. I noticed it wasn't cooling as well as it had been but last weekend it now just blows slightly cool air. Also for about a week before that the compressor started making a knocking noise, almost like its cavitating (very low freon). If figured the low freon switch would cut off the compressor before damage. Anyways, I'm looking for the pressures that the system, should read on my R-134 gauges. I realize that the system pressure is outside temperature dependent but could someone give me some ballpark figures for 90-95F outside temp or a website that might have this info?

About 3 months ago I had to change the expansion valve on the back evaporator, it was leaking/hissing (I posted in this forum). The job went great with no apparent leaks afterwards. I pulled a vacuum on the system and it held for two hours before I re-charged the system. When I discharged the system I used a filter media to check for any oil loss, none noticed. Should I have replaced the compressor oil also?

I'm thinking of simply checking the pressures and re-charging the system to see if I can get the air temp down. If it's not a leak and the compressor has crapped out but is still running I should see this on the gauges, right?

Low side should be about 20 to 45 psi. High side should be 150-300. Evaporator should be 35-40 f.

OK, with the engine off the pressures on both sides read about 75-80 psi. According to the manual over 50 psi is good. With the AC on full (blowing not cold air) the low side reads anywhere from 60 to 80 psi and the high side from 100 to 130 psi this is dependent on engine RPM from idle to about 2000 RPM. The compressor turns on but is making a really bad clicking sound. I'm guessing the compressor has gone kap-put. I can't complain since my wife hasn't let the compressor rest for the last 8 years, hot or cold, rain or shine, winter or summer.

Has anyone changed one of these out on this car. According to the manual the electric fans have to come off the radiator then you basically unbolt the compressor and remove and of course with upper front engine mounts, drive belt and assorted electrical connections.

I am familiar with AC work so I know enough to feel comfortable with doing it myself, my only fear is that this is a Venture van and nothing is easy to get at as it seems.

you have to pull the cooling fans out to get to a/c compressor. then loosen the hose bolt[ when you tighten this bolt go easy as you can strip out the the threads in the al. compressor] then three bolts holding the compressor on. could be just the clutch bearing going out. you have to take the serpentine belt off and get the front motormounts out of your way.the fans unplug in the middle.

I did swap the compressor with no apparent problems. Did it a month or so ago. I got the new o-rings for all connections and changed the drier and filter orifice, to make sure the compressor warranty is good. Also purged the lines with an alcohol based cleaner. Re-assembled, carefull with the aluminum connections, pulled a vacuum and charged with 4 cans of R134a. Working like a champ.

Thanks for all the help in this forum...

glad you got 'er going again. i had to put the shaft seal in my compressor back in the summer and it was fun.... later.