Air Conditioning problem

I have a prob with my R32 a/c system.
Compressor is fine, control unit is ok. I had to change the pressure switch with an aftermarket universal one. I had to fabricate the leads to make it work. Anyway, the compressor will not engage unless you ground one of the terminals on the pressure switch. Fan will nor run either.

Any ideas on what to do. My mechanic is suggesting taking the dashboard down..says there must be a faulty module or something back there.

thanks in advance for the suggestions