Cooling fan issues continue...

sc91gt

Registered User
I've searched and cant pinpoint my issue. Last winter my fan locked up and fried, including the pig tale. It was still frying even with ign off. Had to cut it. Got a used fan and a pigtail from JY. Installed and still wont come on. Switched a supposedly good ircm and nothing. I checked the fan with a jumper from battery. low speed worked, high speed did not. So I bought a new fan motor. Wired it in. Will not come on. Tapped the ircm, disconnected the temp sensor and will not come on. Is there anything else I can check? I have a IC fan on a switch, my only option seem to wire a relay into that from the batt and just have it run full time. Car is a 90, auto, minor bolt ons and a chip from Dave. The chip did kick the fan on earlier... Thanks in advance.
 
With the ECT sensor unplugged, key on, is there voltage at the low speed wire for the fan? There should be.
 
With the ECT sensor unplugged, key on, is there voltage at the low speed wire for the fan? There should be.

I recall David N. reminding that it has to be key on, engine running?

Good idea, in this case, tho.
 
If fan doesn't come on with ECT unplugged and Key in Run position (doesn't matter if running or not) either bad ICRM or Fusible link. I'd go with the bad link, I had same issue when my fan seized.

Link comes off the main cable form the Alternator, Ford solder it originally and without a properly sized iron will be a pain to resolder the replacement.
 
Thanks!

I was wondering if there was a fusible link. Nothing happened when I disconnected the ect sensor. Today I ran a jumper from batt to fan to find which was Hi/lo and new fan doesn't work..
 
The way the controls work is ground is switched and power is constant (basically) so you must manually ground the motor to check if its good.
 
I was wondering if there was a fusible link. Nothing happened when I disconnected the ect sensor. Today I ran a jumper from batt to fan to find which was Hi/lo and new fan doesn't work..

Bear in mind that startup current for the fan can be pretty high. Was your jumper fused, and if so, what amperage?

If you take a hot wire and try to make the connection at the fan motor, you will get sparks and are likely to melt a little spot of terminal right off. Due to the high current draw (seen as basically a short circuit until the motor spins up and the back-EMF starts to oppose current flow).
 
I thought about it and figured the fan need to be a complete circuit. So power and ground to the batt and fan does work. For now I have a 40amp relay direct wired with a switch, 40amp fuse off batt. So drive-able. I will find and replace the fuseable link when ever I get back from next work trip. Thank you guys so much for the help! I'm mechanical, learning electrical.
 
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