Hello people, Once again I could use your help. The attached diagram is for the AC compressor circuit for a 1986 Mercedes 560SL. It uses the N6 compressor control unit to turn the compressor on or off by opening the ground circuit to the compressor. In my custom application I only needed one feature of this controller and that was the S25/5 temperature switch to shut the compressor off in the event of high engine temp. I did this by using a 5 pin relay wired to be normally closed and it would break power on the positive side of the compressor instead of the negative side. It ran fine for several months but then I damaged my N22/2 AC push button controller. The N22/2 is not the mechanical switch as shown in the wire diagram but it uses the push buttons to actuate relays within it. It is a very problematic unit and it is recommended that when it is replaced the N6 compressor control be replaced with it because a compromised N6 controller has been known to damage the N22/2 push button control. So the system is not too robust to begin with. My question is, would switching on the negative side be a more robust solution. And is there any other steps I could use to improve the longevity of the N22/2 AC controller.