Cooling fan does not run with A/C
Thread Starter
2nd Gear
Joined: Jun 2003
Posts: 2
Likes: 0
From: Watervliet ny
Cooling fan does not run with A/C
I have a 87 coupe. My main cooling fan does not turn on when my A/C is turned on. There is a full charge on the system. Both fans run normal. The clutch in the compressor is engaging and then as the pressure builds in the system the clutch will disengage, but the pressue contiues to build so I am not using it and want to. I am looking for info on how to test the high pressure switch. I think that the low pressure switch is ok because the clutch engages and runs. Also is there any way that I can test the ecm that sends the signal that closes the relay and turns on the fan. Any help would be great. Thanks. First post!
Ed
Ed
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: Cooling fan does not run with A/C (capt3210)
Fan switch is on the high pressure line next to the high pressure switch. The switch opens and turns on the fan when the high side reaches about 230 psi. As the fan cools the charge, pressure is reduced and the switch closes at about 170 signalling the ECM to turn off the fan. If you have a manifold gauge set, you can check your pressures. A quick check is to disconnect it. The fan should turn on because that opens the circuit. If it doesn't, the signal wire is grounding somewhere or the ECM may be bad. If the fan works when it's disconnected, the switch is bad or there is something preventing the sytem from reaching 230 psi - low charge, the compressor is shot, high side obstruction before the switch (look for an ice spot).
Thread Starter
2nd Gear
Joined: Jun 2003
Posts: 2
Likes: 0
From: Watervliet ny
Re: Cooling fan does not run with A/C (SunCr)
I just removed the small conector on the small tube and the fan came on. The fan stayed on until I shut the car off. When I restarted the car the fan was not working. It started as soon as I disconnected the small one again. Is that the high pressure switch? If it is, is there a shrater(?) valve in the switch or do I need to recaptur the system?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Re: Cooling fan does not run with A/C (capt3210)
Fan Switch is separate from the high pressure switch. Harness should be dark green & black. High pressure should be light green and black. High pressure switch is normally closed and will open at about 400psi and shut down the compressor. Since the compressor is coming on, high pressure switch is closed and probably ok. Fan switch is on a schrader. ECM is working properly because the fan comes on when you disconnect the harness to the fan switch. If pressures are ok, ie, high side reaches 230psi & the fan doesn't come on, fan switch is bad.
