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A/C Pressure Question

Dirtbuster1 on Sat May 03, 2008 9:15 PM User is offline

Year: 1982
Make: Chev
Model: Corvette
Engine Size: 350
Ambient Temp: 75
Pressure Low: 5
Pressure High: 5
Country of Origin: United States

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?


Chick on Sun May 04, 2008 7:38 AM User is offlineView users profile

The manifold set may not be depressing the shrader valves properly, if you have cooling, and the system is removing water, it's working, and the 5psi is certainly wrong..Feel the suction line, should be cold right back to the compressor.. You could try another gauge set, wouldn't hurt..You don't want to be overcharged...

Email: Chick


Freedoms just another word for nothing left to lose

Dirtbuster1 on Sun May 04, 2008 3:01 PM User is offline


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.

TRB on Sun May 04, 2008 3:12 PM User is offlineView users profile

You need one of the last two adapters listed In this link. Most likely the 3/16th adapter.


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