1989 Supra with ZZ4 V8 A/C Troubles 6000 miles


A friend helped me squeeze a Chevy V8 into an 89 Supra. All works great. I recently attempted to get the A/C running again. It uses an R4 GM Compressor, which is a new Delco. The rest is Toyota. I replaced the Evaporator,Expansion Valve, Dryer and all the o-rings to convert to 134a, it had R12. So I evacuated the system and used Ester Oil since Pag Oil and Mineral Oil does not mix. My problem is the Compressor run all the time, even without Freon. I don't think the High & Low Pressure Switches are working. I want to connect the switches directly to the compressor to bypass the old Supra computer. I will never make that work, Mainly because I am to stupid to understand. I guess the purpose of the switches is to protect the compressor. So is it possible to get those to work without the computer. The dash controls work fine. I just want to protect the system. Any help would be appreciated. The High & Low pressure switches have two wires, One is a ground? But for this to work I need to break the AC power? Please any help would be appreciated. Thanks Johncpa