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Old May 3, 2008 | 08:34 PM
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I was trying to charge my A/C. Pulled a vacuum for 5 hours to make sure everything was nice and dry. 30" of vacuum. Put 1st can in and the compressor started cycling. I finally had to jump th low pressure switch to keep compressor running. Started 2nd can, and about half way I could remove the jumper. I kept watching the gauges and the pressures not building. Finally start the 3rd can and get 5 lbs.

Why am I not building pressure. This is my 1st time changing over to R134A. Finally get about 3/4 of the 3rd can in and stop installing the freon. Still only 5 lbs. A/C is nice and cold, but no pressure. There is a pool of water under the car from condensation. Everything feels great.

Why am I not building pressure?

Help!


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Old May 3, 2008 | 11:59 PM
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Originally Posted by Dirtbuster1
I was trying to charge my A/C. Pulled a vacuum for 5 hours to make sure everything was nice and dry. 30" of vacuum. Put 1st can in and the compressor started cycling. I finally had to jump th low pressure switch to keep compressor running. Started 2nd can, and about half way I could remove the jumper. I kept watching the gauges and the pressures not building. Finally start the 3rd can and get 5 lbs.

Why am I not building pressure. This is my 1st time changing over to R134A. Finally get about 3/4 of the 3rd can in and stop installing the freon. Still only 5 lbs. A/C is nice and cold, but no pressure. There is a pool of water under the car from condensation. Everything feels great.

Why am I not building pressure?

Help!


If you are getting cold air and condensation, you damn sure got more than 5 lbs. pressure in that system.
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Old May 4, 2008 | 08:14 AM
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If it's blowing cold, you've got good pressures as wombvette indicates. I would suspect the gauges. Try another set.
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Old May 4, 2008 | 11:18 AM
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Gauges aren't connected properly or valving is not set to tap them into the lines. Did you completely flush out the old R-12 lines before you put in the R-134?
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Old May 4, 2008 | 03:12 PM
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The 1st set of gauges I was using was a cheap set of Harbor Freight gauges. I have never seen a set of gauges go bad. I have now. I got my good set of r12 gauges out and hooked them up today. I am getting from 27 - 32 on the low side. My hose want hook to the high side. To big for fitting. I not sure what the fitting is on the back of the compressor, but it does not read anything. I thought it was the high until I searched further.

I guess I need to find out what type of fitting this is, so I can check the high side. Other than that everything else feels great.


Thanks for the help.
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Old May 4, 2008 | 03:24 PM
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You're welcome. You need an adapter for the high side which you'll find here (these are hard to find locally in most cases as R12 is becoming a thing of the past):

http://www.ackits.com/merchant.mvc?S...Category_Code=

However, it sounds like you're keeping your R12 service ports. These should be changed to 134a service ports to alert those who are working on the system. They usually come with the 134a conversion kits.

Last edited by Jud Chapin; May 4, 2008 at 03:26 PM.
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Old May 4, 2008 | 03:28 PM
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BTW, what steps did you take in converting your system from R12 to R134a?
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Old May 4, 2008 | 03:36 PM
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The A/C was not working when I purchased the car about a year ago. Doing a frame off restro, I replaced the compressor, Drier, orifice tube, and flushed everything while apart.

I had a hard time deciding between R12 & R134A. Finally I decided that if I was to have some type of problem, R12 could become quite expensive. You here rumors about that all freons will be discontinued or changed. It's a money racket.

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Old May 4, 2008 | 03:41 PM
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Did you change to the 134a compatible oil? This is important.
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Old May 4, 2008 | 07:44 PM
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I installed the PAG 150 that was recommended for GM. I went to Napa, and they tried to sell me the Ester 100. I know that if water mixes with an ester based oil it will start to turn to acid. Gm recommended between a 125 & 150 ISO oil for the R4 compressor.

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Old May 5, 2008 | 12:12 AM
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Good deal. I was concerned that you didn't change to the proper oil.
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