1G No cooling fans when A/C button is engaged.

[Mitsi1991]

So Im having a bit of a head scratcher on my 91 eclipse? Its happened randomly? First my defroster switch stopped working and ive tried a few new known working switches and they still dont work. Ive checked the fuses they are all good. And of course the only way I can keep my motor cool is so click on the a/c and have the fan engage. How ever they no longer turn on when the heating fans are turned on and the ac is engaged? (Note: eclipse doesnt have A/C installed

 

[evil_eagletalon]

Have you verified the fans are or are not getting power?

 

[petrosian]

Check out this post here: 1G Radiator Fan Cooling Issue

Read it through because I put diagrams and explanations in there that I don’t have time to repeat at the moment It should give you an idea of how the circuits work for the fans.

If you have zero fans with the AC switch on, I’d bet you have a relay issue. Check your fuses too, but that’s usually a no brainer. You need section 8 page 100 [Air Conditioner Circuit] of the FSM.

All fan control (both the radiator fan and condenser fan) passes over to a separate relay (the condenser fan hi-lo relay) anytime the AC is on. Does your radiator fan still work after the car is up to temp without the AC on? I bet it does.