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won't hold vacuum

archie on Sat January 16, 2016 4:58 PM User is offline

Year: 1990
Make: chevy
Model: astro van
Engine Size: 4.3l
Refrigerant Type: r134a

hi all, o.k. I assembled the following parts. orifice tube, compressor, accumulator, liquid line. pulled a vacuum for 3 hours. both low and hi side will not hold vacuum. I got a leak. how do I proceed?

Dougflas on Sun January 17, 2016 12:02 AM User is offline

Do you have a sniffer? (electronic leak detector) If not, put a small charge or R134a in it and use liquid leak search on all fittings. Sometimes, the guages are the problem so disconnect them and put the caps on the service ports. To check the compressor seal, I use a plastic bag fitted around the compressor and let it sit for a few hours. Then I poke a hole in the bag and put my leak detector in the hole.

archie on Sun January 17, 2016 7:39 AM User is offline

yes, I have a sniffer. I will do as you say. the system loses vacuum very rapidly, will I be able to put a partial charge in?

Cussboy on Sun January 17, 2016 10:17 AM User is offline

Quote
Originally posted by: archie
yes, I have a sniffer. I will do as you say. the system loses vacuum very rapidly, will I be able to put a partial charge in?


You'll have to do the best you can. You may even be able to hear it hiss as refrigerant escapes just after you add it. Soap bubbles might not work here, the escaping refrigerant might come out so fast. Obviously key on the fittings that you just have assembled.

Maybe take to a shop.

archie on Sun January 17, 2016 3:03 PM User is offline

you mentioned the fittings, just how tight approx. should the fittings be. too tight is bad for o rings, too loose a leak is created. how tight past hand tight?

Cadillac Kid on Mon January 18, 2016 3:59 PM User is offline

Quote
Originally posted by: archie
you mentioned the fittings, just how tight approx. should the fittings be. too tight is bad for o rings, too loose a leak is created. how tight past hand tight?


I usually get them started by hand, then take the wrench and start turning it until it will not spin any more with easy pressure. Like the fitting has bottomed out.. Not serious force applied. Then once I am at that point I turn the wrench just a 1/4 turn more tight. You just want the fittings snug, and that's it. don't forget to lube up the o rings before installing them. It will make them seal better.

-Gavin

archie on Mon January 18, 2016 6:57 PM User is offline

well, thanks to all who answered. I did use nylog blue on all o rings.

mk378 on Mon January 18, 2016 10:59 PM User is offline

When it's a big leak you want to start with literally little puffs of 134a into the system. It is easy to have traces of 134a clouding the air in the garage making the leak detector go crazy all the time.

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