1989 C1500 with an 05 5.3, drive by wire throttle, R4 AC Compressor.

I didnít have any AC issues before the Swap, I left the Compressor hooked up with the system charged and I mounted the R4 compressor with a Dirty Dingo bracket. I used all the stock wiring, but I donít remember if or how I tied into the engine harness. Iíll have to go back and look at the pin diagrams to refresh my memory.

When I turn on the AC, the engine seems to stumble and the tensioner starts to bounce rapidly. I talked to a few people, I had the system evacuated, swapped the compressor, had the system recharged and still having the same issue. Iím on the verge of trying to track down a restriction in the AC system, dryer/oriface tube/blocked condenser etc.

Is there any chance this is a PCM issue and not an AC system issue? I donít have a problem with replacing the dryer and oriface tube to check for a blockage, but I want to make sure I rule out a PCM issue before I start spending a bunch of $$$$.