Chad T

Hey Guys,

I overcharged my A/C for no good reason and blew out the compressor shaft seal. After researching I decided to try replacing it and see how it worked. Installed the seal and put manifold gauges on. Pulled vacuum for about an hour and the system held vac overnight.

Today I charged the system. I started by charging through the high side with the car off. I put 2 12.5 oz cans of r134 in by heating them up in warm water. So then I start the car and get the compressor running (after I re-adjusted the clutch air gap but that's a whole other story).

Low side was just below 30 and high side was just above 100. Air was blowing fairly cold with vent temps around 50 degrees with a meat thermometer. Ambient temps about 83 (could have been higher as it gets hot in my garage). I decided to ad some more 134 through the low side. After doing this I got the low side up to about 35 but the high side wouldn't go above 150.

The big problem is that when the rpms go up the low side pressure drops instantly and the compressor starts short cycling. It does this at anything much above idle. Got worried about overcharging it again so I stopped adding refrigerant. Good news is the seal seems to be holding so far.

I though I might not have been getting enough air though the condensor but it does the same thing when driving. Cycles on and off constantly. Any ideas? I did ad about 4 oz of oil to the compressor since I lost a bunch out of the old seal. Could this be from too much oil? Compressor bad? Still undercharged somehow?

Any ideas appreciated. I know there are a lot of A/C threads on here and I've read most of them. Don't remember seeing this problem before.

Thanks,

Chad

Paul Waterloo

If I didn't know any better, it sounds like the compressor is worn internally and possibly the increase in RPM is causing clearances to open up and pressures to equalize.

That's a hunch.

max_boost951

What's your static pressure reading? Sound maybe a little undercharged. I've never seen overcharging blow out a compressor seal only the high pressure relief valve

Chad T

Pressures are becoming less equal as the high side stays the same at about 150 and the low side drops to around 20. It's possible the compressor is shot though.

Static pressure yesterday at around 83 degrees was about 88. Today with temps in the 60s its below 80. Might have just been the seal's time to go. I'll probably try putting some more in to see if that gets it where it needs to be. Should have plenty from the amount that went in but I suppose I could have lost some.

joes

As the compressor turns faster the "pumping" action increases. I always charge at a fast idle. Pressure should be around 30 (or a little more if everything is hot) at 2000 rpm high side should get around 200 (or a little more if everything is hot). I would put 2 or 3 more ounces in.

william_b_noble

in my experience two cans is too much, so you may well have overcharged it.

Chad T

A/C seems to be working well today. I think I may have screwed with the expansion valve by forcing 2 cans in through the high side with the motor off. Now I'm getting low side pressure of 25 and high side is at 225 (ambient temp low 70s/high 60s). High side pressure rises when I raise the RPMs then the condesor fan kicks in as it approaches 250 and brings it right back down. Compressor is no longer cycling off with rpms. I also purged some of the excess oil per instructions I got from an A/C tech. Getting 38 degrees at the vent so I'll leave it alone for now. Thanks guys.