lhd dc2

My buddy has a problem with his AC System. He has a 94 Integra, and his ac is not working. We got the system tested and there is no power going to the compressor. All of the relays and fuses are good, New pressure switch, jumped the switch/harness nothing happens, and a new climate control. All of the components are replaced from a working car. When we jump the compressor straight to the battery, it kicks on.


Any ideas on what to check or what is the problem?

el crapitan

basically, the compressor clutch is working. what you want to do is work your way back jumping the harness to pinpoint where the problem is.
i would try actually jumping the relay, with it installed, next. see if it engages the clutch.
sometimes a relay will click when tested, but not necessarily be working correctly.
if jumping the relay doesn't cause the clutch to engage, try jumping immediately after the relay. if it engages then, you know the relay is the problem

fcm

The A/C compressor clutch relay is controlled by the ECU/ECM/PCM, as mentioned, jump the relays main terminals, [fuse 56 - 20A must be good] to see if clutch engages, if it does, test the relays coils terminals, one should be 12V+ when ign. is turned on, [fuse 17 - 7.5A must be good] the other terminal is the ground control from the ECU/ECM/PCM, check for ground on terminal with engine running and A/C turned on. 94