Cooling fan won't run

aroot1

SCCoA Member
I know this has been covered many times, but I keep getting overwhelming threads with the search function without the info I need.

Restorecting an 85K mile '90 XR7 that has been sitting for near 10 yrs. Car was taken off the road for a bad comp ground(!!!), fan ran when key was on til I repaired that problem. Now the car runs well, no check engine light, but no fans. Turn on the AC, still no fans. Tried 2 IRCMs that I have on the shelf with no change. Pull the plug on the ECT sensor (pass side of SC sorta under the inlet tube) low speed fan comes on, but so does check engine light. The wiring all looks good (no worn/bare tore up/pinched places). Won't pass an emissions test like this. I am not going to try to fix the AC. I'm heading out to the shop to see if I have a spare ECT sensor right now.

Do these symptoms point to the sensor? IRCM? Should I just clip the brown/orange wire and splice to the pink at the IRCM and b done with it, and if I do that will both fan speeds work or just low?

Right now I just want to get this car running stock and reliable till I trust it. I really am not interested in a chip or tune at this point.

Any ideas/help?

Thank for all replies
Adam
 
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You said the fan comes on when you disconnect the ECT sensor. That means the fan is working and so is the IRCM. If its an overheating problem, its worth a shot at replacing the ECT sensor. They rarely go bad though. After that, its new computer time because there's really nothing left.

If you get desperate.. you can clip the #14 wire (brown/orange) (not the pink wire). Thats it. nothing more. Just let it hang. Fan will run always. Splice it back together when you figure out the real problem. From what I recall, the A/C won't trigger the fan if the A/C itself isn't working. That is empty of refrigerant.
 
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Tbird,

Thanks, that's what I thought. Only other ECC I have is '89, so it would have egr, whereas the '90 does not. Not sure about that. I believe if you jumper the pressure switch on the AC it should still trigger fan even if the compressor doesn't work. Gonna try it I'll post up later with results.

Adam
 
Rock'nRoll!! New ECT sensor fixed it rite up. Scary how hot these rigs get b4 the fans come on:eek: Jumper the pressure sensor at the AC can (condenser?) at the firewall and the AC switch will turn on the fan, kinda cool that.
Thanks
Adam
 
Rock'nRoll!! New ECT sensor fixed it rite up. Scary how hot these rigs get b4 the fans come on:eek: Jumper the pressure sensor at the AC can (condenser?) at the firewall and the AC switch will turn on the fan, kinda cool that.
Thanks
Adam

You want to know when youre fan comes on without a tune? after the point that the engine overheats! :) lol it really is insane! Qh all alluminum radiator and 180 t-stat now i can run the AC on a 100degree day driving it hard and it only hits 206f 70/80 degree day it stays around 185f
 
I'm not sure about the EGR, posts on other threads when trying to figure this out stated that 90 was the only year without it. Might have meant just one of the sensors? That stuff is so buried behind and under the cowl I can't even tell if it is different than my '89!
Yeah, a QH and tune for cooler stat is the way to go, but the plan is to turn this car, and my '89 SC and put all my parts into the "WarBird" rolling chassis I just picked up;) so trying to get it drivable for as little as possible.

Adam
 
Rock'nRoll!! New ECT sensor fixed it rite up. Scary how hot these rigs get b4 the fans come on:eek: Jumper the pressure sensor at the AC can (condenser?) at the firewall and the AC switch will turn on the fan, kinda cool that.
Thanks
Adam
Great. Glad you got it going. And that A/C Can thing.. its the accumulator aka drier. Jumpering the pressure switch will also engage the compressor. If the system is not full, running the compressor will make it lock up :eek: If you don't want that to happen, unplug the compressor itself.
 
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