orangemazdab2000
+1y
I assume you're talking about a standard bosch relay. I'd wire the positive lead of the compressor to terminal 30. Terminal 87 would go straight to the battery with an 8 or 10 gauge wire and with a fuse inline. Terminal 87a wouldn't be used. Terminal 85 should be grounded. Terminal 86 should be a switched 12 volt source like the ignition, with a pressure switch in line. (You could also put the pressure switch on the ground side between terminal 85 and ground if you wanted to) I hope this helps...