R4 compressors

1

1980s

Not-quite-so-new-guy
Jun 26, 2019
33
8
I've been installing r4 compressors on my 1980 Pontiac Grand Lemans and GMC Caballero. One was new and the other was a reman. What a nightmare! About 20 years ago the design of the hose manifold connection changed. The old square-cut o rings were replaced with Mickey Mouse "washers." I finally got the Pontiac working by using a big, plain seal and a green one. That combination didn't work on the Caballero. I had to use a red one and a green one to get the sealing surfaces even before installing the manifold. Three techs at Fourseasons told me different things about the seals. The Caballero system is leaking so I'll spend the day trying to identify the leak. I have no idea why the compressor design was changed.
 
69hurstolds

69hurstolds

Comic Book Super Hero
Jan 2, 2006
2,611
113
Because in the early 90s, they went to R134A, and when they did, the hose connection points got different heights instead of being the same. AKA stepped gasket surfaces. I guess because they were stupid and figured they'd make a "134" version of the same compressor. All the other internal parts are the same, I think. The machining for the hose connection is different. Thus, when you try to use an R12 hose assembly on an R4 compressor, you have a mismatch. Those idiots.

Non-stepped "normal" R12 connection points.


Stepped style. You can see the machining difference.


They try to use step washers, etc., to alleviate this issue, because most ALL of the remans and new R4 compressors you can buy are for 134. I have heard of blowouts using these washers, and it MAY be because they don't use the aluminum inserts that may or may not be included in the GM kits.

Note the washer thicknesses.


They have those washer kits you can buy...

A/C Manifold Seal Kit
ACDelco P/N 15-20058
GM P/N 2724887
These can be found with aluminum extenders and the yellow washer, and sometimes they don't have them. So be aware.


Ready Aire also sells a kit for R12 hose assemblys (non-stepped connector block) with the aluminum insert extenders and a yellow washer, something the GM kit doesn't always have. I wonder where GM gets them...hmmm.
Ready Aire P/N 2728



I think the best thing that CAN be done, is to find like a 1993 or 1994 Chevy truck hose (I think this is when they started using R4s with 134- there may be others as well) and get the connection side of the hose and have it welded on to your hose assembly. I know that's a PITA, but that will cut down on the fat/skinny gasket routine which usually ends up with a leak. ALWAYS look at the connection points when you get a new R4 compressor. Plenty people are unaware when they order a new compressor for a 1981 for example, and end up with a compressor that physically fits the mounts, but the hose connections are stepped. But that's the number that fits your 81!!! WTF? Apparently they no longer make the new compressors for R12.

Hope this helps.
 
1bad79

1bad79

G-Body Guru
Dec 3, 2011
943
93
Allendale mi
I used a r4 with the step and a manifold hose for a 92 camaro on my olds I’m running a serpentine belt but the compressor is in ruffly the same location it might be a combination that might work for you if you have a olds engine
 
olds307 and 403

olds307 and 403

Geezer
Oct 14, 2008
5,053
113
Melville,Saskatchewan
I used a 94 truck hose as well with a 94 compressor for the Serpentine swap. Just couldn't get the high pressure side switch to seal then it sprung a major leak elsewhere, probably at the condensor.
 
1

1980s

Not-quite-so-new-guy
Jun 26, 2019
33
8
I've been installing r4 compressors on my 1980 Pontiac Grand Lemans and GMC Caballero. One was new and the other was a reman. What a nightmare! About 20 years ago the design of the hose manifold connection changed. The old square-cut o rings were replaced with Mickey Mouse "washers." I finally got the Pontiac working by using a big, plain seal and a green one. That combination didn't work on the Caballero. I had to use a red one and a green one to get the sealing surfaces even before installing the manifold. Three techs at Fourseasons told me different things about the seals. The Caballero system is leaking so I'll spend the day trying to identify the leak. I have no idea why the compressor design was changed.
I went through all of the seal combinations but a unpainted one with a green one worked on the Pontiac but wouldn't work on the Caballero even though the R4 compressors are suppose to be the same. I used the green and red ones on the Caballero so the hose manifold would sit square after torquing to 26 lb-ft. No leak so far today. Getting the pressures correct is my latest problem.
 
gnvair

gnvair

Master Mechanic
Sep 1, 2018
355
63
Southern New Jersey near Philly
I went through all of the seal combinations but a unpainted one with a green one worked on the Pontiac but wouldn't work on the Caballero even though the R4 compressors are suppose to be the same. I used the green and red ones on the Caballero so the hose manifold would sit square after torquing to 26 lb-ft. No leak so far today. Getting the pressures correct is my latest problem.
I used the same combo of sealing washers with an OEM GM F body hose assembly and an ACDelco compressor and it seems to be working ok. Time will tell I suppose.
 
airboatgreg

airboatgreg

Royal Smart Person
Oct 2, 2016
1,661
113
They are a pain for sure. Did many of them
 

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