I recently replaced the condenser on the car shown and added a little oil to condenser, vacuumed and charged by weight. AC works great at idle but hi pressure falls off to about 7 or 8 bar at highway speeds (85 ambient, 65 mpg) while blowing ~50's F air at evap based on readout. In shop with gauges hooked up I see the same thing and the low side stays at 30 psi. I can bring the car back to idle and pressure goes up to 12/13 and it goes to blowing cold again. My DD (only difference is it is a diesel) blows 37dF air with 9# showing ambient 85 at 65 mph. On occasion the one I'm working through will increase in pressure slightly and blow colder air than previously although I've yet to see it below 44dF. The one working good got an a/c rebuild a couple of years ago.

No issues with the electric fan. The compressor on the car not really working is original. I'm thinking a new compressor/dryer should fix it right up?

tia

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Jim