1986 Corvette AC Service…was it not done correctly?

[kenlou]

Two years ago I replaced the COMPLETE AC SYSTEM in this car with the help of this forum. I had the system charged by a nearby shop. In the following two years, the car quit cooling so I took it to another shop to get my AC back.
I explained all this to the guy doing the work and don’t understand why he did what he did. I thought I was going to get a working ac system but instead I feel he owes me a complete return of my money.

When he calls and tells me the job is complete, I was happy but when I ask him if he found where it was leaking he tells me he found no leak. I remind him that we know it leaks because the system had lost the complete charge that was put in two years ago and he agrees that it has a leak.


Why did he put in a full charge and not try a little harder fo find the leak? It pisses me off, I will tell you that.

In the meantime, I have found the leak. It is leaking from one of the seals behind the R4 compressor.

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I cleaned it all up and ran it for a short time and shut it off and I can see where the new oil is leaking back down through that seal, why did he not find the leak to begin with?

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I want to change those two seals on that r4 compressor but I don’t want to have to flush any of this. What do I need to do with this?

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It looks like I used the wrong seals initially. That red seal should have been the gold colored one.
Is there any thing I could put around those two seals on the compressor to stop a leak there?

If I disconnect that main line connected to the compressor to change those seals, can I get by with just changing the accumulator?

[Cusser]

Disclaimer: I'm NOT an AC professional. But I have a certain amount of knowledge and hands-on experience.

when I ask him if he found where it was leaking he tells me he found no leak. I remind him that we know it leaks because the system had lost the complete charge that was put in two years ago and he agrees that it has a leak. Why did he put in a full charge and not try a little harder to find the leak? It pisses me off, I will tell you that.

1. Many shops will do a charge of refrigerant and UV dye then have you come back in a week so they can find the leak with UV light. Could this be what that shop intended?
2. That shop can recover the remaining refrigerant, then install new correct seals and then recharge.

In the meantime, I have found the leak. It is leaking from one of the seals behind the R4 compressor.

Good start !!!

I want to change those two seals on that r4 compressor but I don’t want to have to flush any of this.
If I disconnect that main line connected to the compressor to change those seals, can I get by with just changing the accumulator?

If a new accumulator was installed after the car sat for 2 years and that shop then charged it, if mine I would not replace the accumulator again. I would get new correct seals in advance, have the refrigerant recovered, install correct seals, then evacuate and re-charge. The R4 compressor has the low and high lines in a combined manifold held in place with one bolt, so BOTH seals must be replaced.

If that shop did NOT replace the accumulator then, that was a huge mistake and they should process a refund or partial refund.

[kenlou]

Many shops will do a charge of refrigerant and UV dye then have you come back in a week so they can find the leak with UV light. Could this be what that shop intended?

Probably

If a new accumulator was installed after the car sat for 2 years and that shop then charged it, if mine I would not replace the accumulator again. I would get new correct seals in advance, have the refrigerant recovered, install correct seals, then evacuate and re-charge. The R4 compressor has the low and high lines in a combined manifold held in place with one bolt, so BOTH seals must be replaced.

I have the new seals and accumulator. I was planning on going back and explaining what I found and have him recover the refrigerent so that I could make the repairs at home and do the vacuum myself and once satisfied take it back for him to finish. Would I be better off him doing it himself?

I live in Washington Illinois and I am limited as to finding a really good mobile ac shop also.

[kenlou]

Another question….
When a system loses it’s complete charge how do we determine how much oil is left in the system and how much needs to be added back?

If I change only the accumulator how much oil should I add to it?

[JohnHere]

It's been quite a while since I worked on that particular model-year vehicle, but I seem to recall that the compressor and manifold have shallow circular reliefs cut into their respective flanges, into which the seals fit. Then the center bolt is tightened to partially compress the seals to such an extent that the flanges meet. I don't recall the sides of the seals showing as they are now. Seems like something's wrong there.

Another question….When a system loses it’s complete charge how do we determine how much oil is left in the system and how much needs to be added back?

Two ways: by guesswork, or by starting with a "dry" system. Unfortunately, there's no way to gauge the amount of remaining oil in an assembled system unless you're starting dry and adding the total amount according to the manufacturer's specifications.

Since removing all the oil by flushing isn't in the cards (and I don't blame you), we'll have to guess at the amount of oil lost due to the leak. Usually, it's just a trace amount due to very slow refrigerant loss, not like the oil is gushing out of the leak to the point of being empty. How much would you guess the system has lost?

Given the nature of the leak and the two-year time span, I'd guess maybe 1/2-ounce. Oil leaks often appear worse than they actually are. If that seems too much, remember that it's always better to add a little more oil (within reason) than not enough. The latter situation will "starve" the compressor of lubrication and eventually cause it to fail.

If I change only the accumulator how much oil should I add to it?

To know for sure, consult the oil-balancing section of the Field Service Manual for your car, AllData, or Mitchell's. The amount of oil to add to a new accumulator is usually around 2 fluid ounces but can vary.

[kenlou]

It's been quite a while since I worked on that particular model-year vehicle, but I seem to recall that the compressor and manifold have shallow circular reliefs cut into their respective flanges, into which the seals fit. Then the center bolt is tightened to partially compress the seals to such an extent that the flanges meet. I don't recall the sides of the seals showing as they are now. Seems like something's wrong there.

That picture showed the wrong seals that I installed. I have since installed the correct seals. In place of that red seal, there is now a gold colored seal that is larger in diameter and fits properly.
Also the back of that new R4 compressor has stepped ports that require these washers where as the original ones used orings that allowed the block to seat to the back of the compressor.


Chevrolet Service Bulletin
Bulletin Number: 92-35-1D - (10/11/1991)

When using sealing washers, there will be an intentional "gap" between the compressor rear head and the air conditioning hose assembly block (suction discharge block assembly). Do not mistake this as a loose connection or a mis-assembled joint.

I added 2 oz pag oil to the accumulator and pulled a deep vacuum down to 310 microns and holding steady. I am getting back to the shop Friday to have it charged.

If you recall this had been converted to r134a with your help