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1972 Chevy truck cooling problem

Sendd on Mon August 16, 2010 3:14 PM User is offline

Year: 1972
Make: Chevrolet
Model: 1/2 ton pickup
Engine Size: 350
Refrigerant Type: R-134
Ambient Temp: 92F
Pressure Low: 29
Pressure High: 220
Country of Origin: United States

I have a 1972 Chevy 1/2 ton pickup that I have had since it was new. My problem is that my ac quit cooling after the truck was not driven for 3 weeks. The compressor is the A-6. The sight glass shows refrigerant to be flowing. The low side reading at the POA valve is 29 psi and the high side at the compressor is 220psi. The large line entering the POA valve is just barely cool while the smaller equalizer line is colder. I was wondering if my POA valve has closed or if something else is the problem. I will appreciate any information.

Dougflas on Mon August 16, 2010 11:32 PM User is offline

It appears that your POA is calibrated for R12, not R134. Normalize the system, run at 1200 to 1500 RPM with a fan in front of the grill. Disconnect the blower motor lead. Low side should be 26 psi. If not, the POA is not calibrated for r134. Do a search for POA calibration. The procedure is shown.

Sendd on Tue August 17, 2010 3:08 PM User is offline

Dougflas, thank you for your input. The POA has not been reset and I know that will make a difference but I was getting cool air out of my vents that was 30 degrees cooler than outside ambient air before the 3 weeks of none use. The R134 was installed in Sept. 2006 and has been working OK up until I didn't use the truck for 3 weeks. If you have any other thoughts on this I would appreciate hearing them.

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