1991 AC leak

[someotherguy]

Decades ago I had an R4 that would hold vacuum apparently fine, but when you would try to charge the system, it would leak around the shaft seal.

Richard

 

[tsr2185]

I couldn't see the leak on my compressor until I pulled it and saw the bottom ...but it was a pretty old compressor....

Noted. Its a delphi thats all i know. Not sure if it is stock or not. Im down south so im sure it was used a lot. It also sat for 4 years before I bought it in 2020.

This ^^^

The R4 compressors (you said it's a 1991 retrofit) are known to leak, check for leakage around the input shaft and the body of the compressor.

There are YouBoob videos on how to replace the R4's seals, you might take a look at a couple just to familiarize yourself with the leakage paths.

Someone earlier mentioned the valves; they can be a problem too but it appears OP has checked them (yes?).

If it was your evap, I would expect to see it coated with dust wherever the oil leaked from the system onto its fins.

Do i have to pull the clutch to check the shaft? I may look into that, im pretty savvy with the aid of youb00b videos lol. I changed the shrader on the high side, but I didnt relly check the low side port.

Can the caps, if snug enough, slowly bleed the system? I was wondering that because I snug em up pretty good with the **** roads we have around here.

 

[1998_K1500_Sub]

Noted. Its a delphi thats all i know. Not sure if it is stock or not. Im down south so im sure it was used a lot. It also sat for 4 years before I bought it in 2020.

I assume it's an R4 compressor b/c that's what the mounting brackets (on the engine, for 1995 and prior) were designed to hold. The HT6 compressor (which is a known leaker, at the mid-body seam) was used on 1996 and later AFAIK.

If you bought it in 2020, I'm guessing it's already had prior AC service and somebody may have put dye in. Get yourself a black light (borrow from parts store) and look around, see if something glows in the dark.

Using a black light on my S10's R4 I spotted leakage that was not evident to the naked eye... the clutch and surrounding brackets "glowed" with oil spots from the leaked and "slung" oil that found its way out past input shaft.

Do i have to pull the clutch to check the shaft?

No, see above.

Can the caps, if snug enough, slowly bleed the system? I was wondering that because I snug em up pretty good with the **** roads we have around here.

One of the service fittings' caps purpose is to help seal the valves from leakage.

 

[tsr2185]

I assume it's an R4 compressor b/c that's what the mounting brackets (on the engine, for 1995 and prior) were designed to hold. The HT6 compressor (which is a known leaker, at the mid-body seam) was used on 1996 and later AFAIK.

If you bought it in 2020, I'm guessing it's already had AC service and somebody may have put dye in. Get yourself a black light (borrow from parts store) and look around, see if something glows in the dark.

Using a black light on my S10's R4 I spotted leakage that was not evident to the naked eye... the clutch and surrounding brackets "glowed" with oil spots from the leaked and "slung" oil that found its way out past input shaft.



No, see above.



One of the service fittings' caps purpose is to help seal the valves from leakage.

Very good info thanks! I will find a black light when i get one and check it out.

What i meant by the caps is if they were TOO tight, could they hit the tip of the schrader and cause a slow leak. I ask because I got em pretty snug, and I knew I had a leak on the high side because it would PSSST when I unscrewed that cap.

 

[1998_K1500_Sub]

What i meant by the caps is if they were TOO tight, could they hit the tip of the schrader and cause a slow leak. I ask because I got em pretty snug, and I knew I had a leak on the high side because it would PSSST when I unscrewed that cap.

Yup, understood... "too tight" shouldn't be a problem, just don't twist off the threaded portion b/c it'll be left inside the fitting if you do.