90 lumina a/c problems?

[amopar4me]

1990 Lumina 3.1 A/c fully charge and works when I jumper the ground side of the relay All hot leads have been check, both compressor switches in rear of compressor were replaced when unit was last serviced. Ohm them and the wiring to the computer( with battery disconnected) wiring harness @ proper pin location. The coolant fan does not come either but that might ground after compressor get high side up....but jump its ground and its works properly.. have replaced the ect sw under thermostat also..ran out of ideas or what to ck next for grounding side.. thanks...

[DAB77]

The relay gets the ground from the ECM. Check the high pressure switch. Normally closed , should have continuity until pressure is too high. Check light green wire from control head to high pressure switch and light blue wire from switch to ECM