76 Scamp A/C

Pete in NH said

You want to make sure you have no hot water flow through the heater core or the A/C will be trying to overcome the heater.

How much R-134A did you charge the system with after changing the compressor? Your low side pressure at 10-15 pounds looks on the low side. Did your new compressor come with a EPR valve installed internally. A true 76 A body compressor would have an EPR valve. Before about 1974 A body cars used a cycling switch after that they went to an EPR valve like the B and C body cars.

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I think that the heater valve is sticking open some because both hoses are hot, but I also don't know which one should have the valve on it. Without being in front of the car, I believe I have it on the one that goes to the water pump. The new compressor didn't come with an EPR valve and the old one is rusted over and basically trash. I charged the system with 36 ounces of R134a and one of those little cans that's supposed to be an ester oil charge just because I had spilled some when I was filling it before it went on the car. I still need to get a cycling switch and I thought someone had posted a link to one in this thread, but I can't seem to find it, so I'll just do some research on that.