So the compressors are 12volt/32Amp when running.
What is the startup current, and where are you getting that (100-200Amp?) from.
The relays can only handle 10 Chinese Amps...
Seems your first problem is having to look for bigger relays, and big kickback diodes across the load.
Or four beefy mosfets with mosfet drivers and kickback diodes.
Sensing if a compressor is connected is the easy part. Leave that for last.
Leo..