No Measurable High Pressure GM A6 Replacement

[1GCamaro]

sometimes this problem is caused by guage set, this can be diagnosed if still in vacuum by static charging thru high side (with engine off) refrigerant should go thru high side and low side guage will rise, another way to tell if guage set ok would be when system is in a vacuum loosen low side hose at guage set , high side should rise to atmospheric pressure, if not I would say blockage in system, is there a possibility AC suction/discharge reversed at compressor?
Please post solution when you find it

On the A6 there's really only one way to connect the manifold, but that possibility did cross my mind. I noticed that when I was attempting to charge, the Low Side pressure would drop to almost zero as soon as the compressor switched on -- and then when comp was off, Low Side pressure rose fast.

I'm going to run a few more tests to rule out the gauge set - and to try and determine if the High Side port on the muffler is somehow blocked internally (even though the path thru the muffler is open). After flushing they system again I know there are no blockages. Dryer and TXV are new too.

Thanks for the replies and ideas!

[Tim]

Never flush mufflers, it's just a baffle. Almost impossible to get all the flushing agents back out.

[1GCamaro]

Never flush mufflers, it's just a baffle. Almost impossible to get all the flushing agents back out.

A messed-up muffler could be the reason I was seeing such weird readings on the high side (EDIT: Nope - see next post in the thread): No high pressure reading at all -- AND still seeing negative pressure on the high side when manifold pulled off compressor. I think I need to get rid of the muffler. What's the best way to do that without getting a new manifold connector?
Here's a stock photo of what this looks like

ACConnector.jpg (20.38 KiB) Viewed 9853 times

[1GCamaro]

IMG_3970.JPG (81.11 KiB) Viewed 9853 times

How about this messed-up red gauge hose fitting!! Yep, my false readings are caused by this. I ran some vacuum tests, shut it down, and any time I'd open this end, the gauge would drop to zero. Opening the fitting at the other end made no difference. This is a Autozone Loaner gauge set. Lesson learned.

Still doesn't explain why the compressor blew, or why all the oil was in the evap. One step at a time ....

[tbirdtbird]

Most of us service the seals on our hoses on a regular basis. I actually leave my fittings loose until I actually need them so as to not crush the seal to death

There has to be a way to have a new custom line made to eliminate that muffler.
Tim might have something like this available, just change the pad mount.

[Dougflas]

Keep the muffler. Just do something about the connector fitting. Why not pruchase your own manifold ? You will use it enough to make your money back.

[JohnHere]

Ahhh..."bubble gum" in the high-side hose fitting. That'll do it every time!

I agree with Doug. Why not invest in your own manifold gauge set? That way, you'll know what you have, that it hasn't been messed with, and you can maintain it yourself as needed. Purchase a good one, not a bargain set. It'll be well worth the money in the long run. I have three quality sets, so if one acts up for whatever reason, I can switch to another one. I check all the seals every time, and cap all the ends when not in use.

That leaves the oil issue, why it collected in the evaporator, why it left the compressor sump dry, and resulted in the clutch squealing. Even the best vacuum pump won't pull "ounces" of oil out of a system or transfer it from the compressor to the evaporator. Doesn't leave much left to suspect except the compressor and possibly the TXV.

Let us know what you find.

[Tim]

As for the hose, cut the muffler out, weld barb, and replace a section of hose.

Places like Cold Hose can do it. Best to find someone locally. Then there is buying the tools to do it which are not cheap.

https://www.ackits.com/52-0003new-hydra ... 52-0003NEW

[1GCamaro]

Update: After re-flushing, installed new compressor, vacuumed system down, noticed new comp was very, very hard to turn by hand. Since the A6 needs to be turned this way to get the oil out of the cylinders, this was a concern.

I was having some other work done on the car (worn pitman arm, quadrajet work) so went ahead and asked very good certified tech guy to look at the A/C. He agreed the comp was super-hard to turn but went ahead and turned it, charged system, added the remainder of the oil, and system cooled great for about five minutes. Pressures were correct. You know what's coming next, don't you?

Next: Squeal, screech from clutch and belt. Another bad compressor!

Considering a Pro6Ten type A6 direct replacement. Would like to keep the stock look but will give in to this situation to have a functioning A/C.

Edited to add this comment: Removed second compressor, recovered 5 oz of oil from the sump. This compressor still had a good bit of oil in it and was screeching and screaming with pressures correct and cooling -- but engine was being bogged down much more than usual with this A6. Awful.

[Tim]

Both new a6's are available if you don't have sources already.

No comment on the rebuilt unit. Been discussed here for 20 plus years.