Re: GM AC compressor (delphi harrison #6581) malfunction? or just need freon?

thanks very much, paul and steve.

I have an old vacuum pump, but it'll 'pull' only 27 lbs max vacuum. still short the gauges, but the vac pump has an old vacuum gauge (from a car tester) hooked to it with a sort of two-valved manifold 'of sorts'.

I'm wondering if I could judge how bad a leak I might have by hooking it up, pulling it down, isolating just the gauge to the car AC system, and seeing how long the vacuum -does- last. how long 'should' it last? minutes? days?

is 27 lbs of vacuum 'enough'? or does the factory recommend 30 lbs?

also, say I pull a 27 vacuum on the system: at what 'rate of leakback to ambient' is a 'fix your leak first -prior- to recharging' situation adviseable? for practical purposes, is there a rate of leakback to zero vacuum over time 'acceptable', generally speaking? please describe?

so, you're saying 134a is available 'over the counter' in most auto parts stores?

on a related note: don't most car AC systems 'leak down' over time? the car was new in 1999, so it's been, uh, 4 yrs. isn't having to recharge from time to time 'normal'? how long does a 'typical' system refrigerant charge (if there is such a thing) _last_?

is there any practical way for a guy to determine IF the front compressor seal is bad short of either dismantling the compresssor OR using a (very expensive) sniffer device? guess I'm asking how an old 'po boy' might isolate a leak to a known spot (seal? hose fitting? maybe?) 'short of' having a sniffer -is- there a way?

in any event, once the system is 'opened to atmosphere', is a new receiver-dryers recommended? (thirty yrs ago, that's what they were called - maybe they're called something else now?)

again, thanks much, for educating me

Reply to
bill yohler
Loading thread data ...

Answers in line...

If you don't see any movement in hours that is a good sign. I have heard that the compressor seal will leak as it is designed as more of a one way seal.

27 is all you will likely get even with a new pump.

I can't answer this one. If it was mine and it leaked back to zero I wouldn't charge until I found the problem.

auto parts stores, walmarts, kmarts, practically every place with an auto department (atleast in the south... your state/country may vary)

Yes they do. The compressor shaft seal leaks.. The o-rings leak. The hoses leak. Most of these leaks are miniscule but over the years they add up. If yours is only low and you have hoses I would charge it back up and see what happens. Maybe use a can of the stop leak stuff. Might buy you another season or two if there is a leak.

This po-boy takes them to the a/c mechanic and has him check for leaks. The tester will generally give you an idea of how big the leak is. Around here I can usually get them to check it out for $20. There are some that give free estimates but I never felt right doing that when I knew I wasn't going to have them fix it.

Yes. It is still the same part. Don't pull the caps off of it to install until you are ready to pull a vacuum as you don't want it to get saturated.

No problem. Everything I know about A/C came from this group or from hard knocks. Always glad to share when I can.

Steve

Reply to
Steve B.

When you go to the parts place (or Wally World) look for a cheapie A/C pressure gauge. I've seen them - very much like a tire gauge. There should be some pressure in the system, check it without running the engine. If it's close to 100 lbs. or over, adding gas won't do a bit of good. If it's low but still shows some pressure, add the 134. You are right to be careful with the system. 134 reacts badly when it gets air inside. I wouldn't vacuum it if there is still pressure. I'm betting on the slow leak and that a can or 2 will make it cold again. As Steve suggests, a can of the stop-leak stuff won't hurt. I got some last year for a R-12 system that had no gas at all - it was contained in a plastic tube with a screw at one end. Tightening the screw forced the stuff into the system.

When I charge a system, I connect things to the can first, then crack the valve a bit to allow gas into the line as I attach it to the car. I don't want any air in there and this is the best system I have found. The A/C should usually be running when you charge it.

Good Luck!

PoD

Reply to
Paul of Dayton

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.