3800RS

iTrader: (15)

charged the ac in my dd, 96 lumina. It worked at the time and was cold. I didnt have a gauge. It no longer works, clutch doesnt engage and the pressure is a little on the high side at 55psi.

Is there a way to lower the pressure and that would make it engage again ?

3800RS

iTrader: (15)

depressed the needle, pressure is right around 35-40 now. Compressor still does not kick on. All fuses seem fine. I took the 2 wire connector off the compressor and tested it with a test light and got nothing.

Any insights ?

3800RS

iTrader: (15)

swapped the relay with a different one, nothing. I hotwired the compressor and added some r134, it got cold but the second i take the hot lead off the clutch stops spinning.

fleetmgr

What's the high side pressure?

3800RS

iTrader: (15)

i dont have a gauge for high pressure. I fooled with the key on and off and what not a few times and it works now.

I get the suspicion it might leak though.

slow

iTrader: (7)

Why do you think you need to have less than 55psi?

Assuming you need to run the AC, we can safely assume the outside temperature is 75 degrees. At 75 degrees the R134a in the system should be 78.8 static pressure. Below is a good chart.

http://www.acsource.net/acforum/view...php?f=1&t=8490

At this point, I would assume your charge is wrong, and you should have the system evacuated and charged to the correct weight.

You are probably correct, the system leaks and that is why you had to charge it. I would find the leak and correct it. If the car was mine, I would replace all of the O rings just to be safe as well as the drier if I had to open the system up.

Ryan

3800RS

iTrader: (15)

the silly gauge i had said 35psi means charged. i am not really sure, you are saying it should be higher ? it was about 90degrees last night doing it

fleetmgr

I'll assume you're looking at a gauge on a can of gas. It's worth exactly what you paid for it, and trying to troubleshoot with most of the story missing by just using one gauge means you've shot yourself in the foot before you even start.

I agree with slow. Time to take it to a pro, have it evacuated properly and recharged after the leaks are fixed. Your most likely leak point is the crankshaft seal on the compressor, and the only way to fix that is with a new compressor. But, all the seals need to be looked at. Don't waste time with dye...go to Harbor Freight for an electronic detector ($70) if you want to do it yourself.

Once you have the system at the correct starting point, you can look for other problems if there are any.

samson_420

iTrader: (1)

I never liked my Snap On sniffer, it cant find ****. Maybe it's just the one I have. I seem to have better luck with the dye method.


Either way, you need tools man. A pressure gauge on a can is as good as using Motor Honey when your car starts smoking.

3800RS

iTrader: (15)

wow, didnt know those gauges sucked that bad. So inreality what should the psi be like 75 ish for correct operating ?

rbaksi

iTrader: (2)

Aren't the gauges that come with the cans supposed to measure running pressure? That site gives figures for static pressure on the low side with the AC system off correct?

fleetmgr

The gauge couldn't care less if the system is running or not. The problem here is twofold:
1. Knowing enough about how the system operates to be able to correctly interpret the information you have.
2. Having gauges accurate enough to provide meaningful information.

With any refrigeration system, seeing the pressure with the system in a static state will accurately tell you what the ambient temperature is assuming all is as it should be, but it won't tell you anything else. If the pressure is higher than this, you probably have air and/or other non-condensible gasses in the system. Google "Dalton's Law of Partial Pressure" for why this is true.

You absolutely cannot accurately troubleshoot an A/C system on the basis of a single point reading. The best you can do is make a guess.