a/c works fine until engine warms up enough to kick on the cooling fans then a/c compressor won't engage until cooled down?
2005 taurus a/c quits working after engine warms up on 2005 Ford Taurus
You'll need to diagnose the electrical circuit that supplies power to the A/C compressor and that should determine the where the fault is.
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take a look at the coolant level. it is possible that it is high enough to keep engine cool but not at the same time with ac on. ac generates more heat and thus the ECU will shut down the compressor if it needs to.
also check coolant temperature sensor.