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Wierd pressure test results

70GS455 on Sun October 19, 2008 5:02 PM User is offline

Year: 1987
Make: Buick
Model: Regal
Engine Size: 3.8turbo
Refrigerant Type: R134a
Ambient Temp: 70
Pressure Low: 25
Pressure High: 160
Country of Origin: United States

I retrofitted this Regal from R12 which had been in-op (leak?) for 3 or 4 years. I put in a new accum./drier, added 4 oz ester, new or-tube (white), changed all o-rings, new hoses. I used nitrogen to pressure test. First at 125 psi, all was fine, no leaks, held for a few minutes. I increased the pressure to 200 and now had a leak coming from the compressor. It was audible (hissing) and would not hold pressure. I manually turned the compressor and no change. So I decided to not let a technicality stand in the way of progress. I put the vac pump on and left for lunch. An hour later, came back and vac was good and held for a few minutes. First filled with a can of high mileage 134 which had a leak stop in it. Filled the rest up, adjusted the cycling switch to 23 psi and had 160 psi high side at 70 deg F ambient (eng fan running). Had 42 degrees out of the center vent on max/hi. A day later, and so far so good. Any ideas on what the leak could've been? How would it hold a vac with such an obviously large leak?


HECAT on Mon October 20, 2008 6:49 AM User is offline

A compressor shaft seal can leak under pressure and seal under vacuum; as well as many other bad seals that can be sucked into place and seal. Check closely for leaks around the compressor now it is charged. If you find it to be a leaker, I would recover the refrigerant, flush out all the "junk" (old mineral oil, ester oil, and sealer), replace the compressor (OT and accumulator again), and charge with the proper amount of fresh oil and virgin (no sealer) refrigerant.

"high mileage" refrigerant? If you can see beyond the marketing hype and read between the lines; that reads "for your wore out POS". The sealer stuff is just not good for a proper repair. It is just "used car dealer trick #132" (aka snake oil) and it will at times do more harm that good by clogging critical orificed passages.


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Chick on Mon October 20, 2008 10:09 PM User is offlineView users profile

Flushing procedure

Procedure for retrofitting to R134a

Vac/charge procedure

There are no shortcuts in AC repair. Flush the system of all the old junk, replace the compressor, new would be best change the accumulator again, it's contaminated with the sealer and "high mileage" additives, change and inspect the O tube for debris before flushing (change it after flushing) Use either PAG 150 or a quality ester like BVA auto 100 add back "8" ounces to the system, pull your vacuum and recharge using the procedure listed above, sit back and enjoy cold air.. Hope this helps..

Email: Chick


Freedoms just another word for nothing left to lose

JJM on Sun October 26, 2008 12:17 AM User is offline

With a 3.8 turbo, isn't this a Grand National? If so, what a shame to convert to R-134a. Sealer only adds insult to injury.

It's cooling good for now because it's only 70F. Wait until it get's to 90F or above, that stock tube and fin condenser won't keep up. You'll need a PF condenser for R-134a and probably some fan enhancements.


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