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1965 Pontiac Tempest - R134a conversion

dray8165 on Fri May 08, 2009 5:59 PM User is offline

Year: 1965
Make: Pontiac
Model: Tempest
Engine Size: 326
Refrigerant Type: R134a
Ambient Temp: 85
Pressure Low: 26
Pressure High: 150
Country of Origin: United States

Just wanted to post a success story and a thank you for one of the senior members.

I just finished a conversion on a '65 Tempest I am restoring. The car is equipped with a POA valve which maintains a preset continuous low side pressure to the expansion valve. This is a phenomenal piece of engineering which made for a legendary ice cold MVAC in cars of this era. The problem is, with the different pressure / temperature curves between the stock R-12 and 134a, a drop-in refrigerant change does not work well.

In steps Doug Kahane ([email protected]) - a master a/c guru. He has the equipment and know-how to test POA valves and adjust them to work with the new refrigerant. I sent him my 44 year old POA valve and had it back within a week. For a very modest fee, he tested it and adjusted it to the appropriate delivery pressure for 134a.

While the POA was out for modification, I replaced the clutch bearing on my stock A6 compressor (it was grinding) - drained it of oil, flushed my system of old oil, replaced my o-rings (ACkits part # CP3011) , and replaced the drier.

When the POA returned, I installed it, added 8 oz. of PAG-150 and vacuumed the system. I kept it at a full vacuum overnight, then charged the system with 3 lbs. of R134a (the stock system took 4.12 lbs of R-12) Vent temperatures are running at 46 degrees at an idle, and really cool down on the road.

A caveat about the POA system - since the POA maintains a preset low side pressure - you cannot use low side pressure as an indication of how much freon to add. You have to know the capacity and use that to determine the quantity of freon to use. R134a quantity is 80-85% of what R-12 would have been.

Thanks to Mr. Kahane, my 44 year old a/c system is ice cold.

Edited: Sat May 09, 2009 at 1:50 PM by dray8165

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