[AMC-list] 1964 Classic A/C problem

["Carter Braxton" <cbraxton@xxxxxxxxx>]

I'm trying to help out a friend out with the air conditioning on a 1964 Rambler Classic. Someone else did a half-hearted R134 conversion on this car that did not work out. (The dryer had not even been changed.) Symptoms were no cooling and gauges showing the low side going into suction and high side pressure only about 120 psi on a warm, sunny day. The compressor is new and the hoses were rebuilt with the original fittings.

What we have now done is to flush out the evaporator and condenser to get rid of any debris and old oil. (Quite a bit of grunge came out.) A new expansion valve was fitted, the compressor oil drained and the factory recommended amount (7 oz.) of ester oil installed. In order to maintain stock appearance, the original dryer was sent out to be rebuilt. The rebuilt dryer was installed and the system drawn to 30" vacuum for about an hour and a half before recharging with R134.

After all this, the car still has the same symptoms -- no cooling, with suction on the low side and ~120 psi on the high side. Basically it seems like there is a blockage somewhere in the system. I also noticed that there is a check valve going into the dryer. It appears to be integral with the fitting on the high-pressure hose that connects the dryer with the expansion valve, and attaches to a fitting on the side of the dryer.

On my own car I've had the experience of a brand-new defective expansion valve causing this kind of symptom. However, looking at that 45-year-old check valve I'm a bit suspicious of it. How likely is it to be causing this problem? Is it really a necessary component? (My 1975 AMC service manual shows what is basically the same system, but there appears to be no such check valve at the dryer.) If the check valve is needed, are they still available?

------------------------- 
    Carter Braxton
  cbraxton@xxxxxxxxx
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