I'm working on a 92 loyale 4wd wagon AT and AC. When I select anything on the panel the AC compressor runs and cycles on and off while its running down the road. I can tell because it pulls on the engine when the compressor engages. I have seen defrost cycles run the AC compressor on some cars, but not the heater. Is this designed into these cars? This is the 2nd panel I have changed on the car because the vacuum valves inside the panel dried up, but both have acted the same way with respect to the AC running. Any suggestions or help is appreciated!