1999 Blazer AC compressor replacement

[Nandy]

Im just wondering, is it possible for a system that will hold pressure fine to not hold a vacuum? The reason I ask is that I am replacing my blazer compressor with an used one. I know the ideal situation will be to replace the compressor with new gaskets, make sure it has the proper amount of pag 150 oil and then purge the system with a vacuum for about 30 min, close your gauge valves and make sure the vacuum reading dont change, vacuum it again for 30 to 60 min then load the system with 134. However, have any of you that do this seen a system that wont hold the vacuum be able to hold the charge?
The compressor I got dont seem to hold vacuum or the new seals are not good. However, when I removed the compressor from the vehicle that had it in it still had pressure on it so I feel the compressor is fine... I can plug the hoses with my hand, do a vacuum and it hold for over 2 minutes without a sign of losing any vacuum, but once I hook the compressor it dont hold vacuum. I am very doubtful it is the seals, not only I have tried 2 new sets, I have also use the green regular seals and it shows the same problem...

Thanks!

 

[Tim Frank]

Re: 1999 Blazer AC compressor replacement

Hiya Nandy, LTNS.
If it won't hold a vacuum, there is a leak.
You already "know the ideal situation". If you cut corners it will probably bite you....I know I always get bitten when I take shortcuts...

 

[dolluper]

Re: 1999 Blazer AC compressor replacement

Did you lube the seals with pag oil....drop them in bottle cap of pag before assembly

 

[Nandy]

Re: 1999 Blazer AC compressor replacement

I lightly lubed the seals... I have to change that compressor anyway, it sits a tiny too high and my serpentine belt don't fit....

 

[DECK SWABBER 58]

Re: 1999 Blazer AC compressor replacement

As stated, if it won't hold vacuum it won't hold refrigerant. Not holding vacuum is usually the sign of a fairly large leak.
You said the compressor had pressure when removed from donor vehicle. Was their a lot or just a little hiss. This particular compressor is notorious for leaking in the joints of the compressor body. Also due the age of the vehicle an evaporator leak is also common. Sometimes you can remove the blower resistor from evap. case (under the hood) and look in with a flashlight and check for an oil stain. Quickest, easiest might be to just swap out compressor and see what happens.

Good Luck.

 

[RogersJetboat454]

Re: 1999 Blazer AC compressor replacement

I'm quite sure your blazer will hold refrigerant...

For hours to days, maybe even weeks if you're lucky.
Like Deck Swabber said, don't assume that everything else on your truck is in tip top shape. If it were me, I would probably put a charge in it with UV dye. Run the system for a while, then take a black light to it to see if there is any dye stains around joints, seals, hoses, cores, the "new" compressor, etc.

 

[Nandy]

Re: 1999 Blazer AC compressor replacement

ok, just wanted to make sure, I will order the replacement compressor tonight.