Cooling fan Troubles.
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Instructor
Joined: Sep 2003
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From: Pemberton Minnesota
Cooling fan Troubles.
I noticed my primary cooling fan was not working. Switched the plugs at the relays, and had the secondary fan working with A/C on from both relays. I replaced the primary, and started the car to make sure it was working. Primary ran, but the secondary did not come on. Switched relays, same deal. Now the primary would run, but not the secondary. I jumped the terminals on the ALDL, and both fans came on. But neither temp, or turning the A/C on will turn on the secondary fan on now.
Anyone seen this before?
Anyone seen this before?
Thread Starter
Instructor
Joined: Sep 2003
Posts: 169
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From: Pemberton Minnesota
It's a 92.
It got warm in traffic, but almost did what it was supposed to do. Primary did'nt kick on, but secondary took over from about 230 and took it down to 215. That's when I first checked, and found the primary did not work.
It can't be a fuse, because when I jumped pins a and b, both fans turned on. Before I replaced the primary, only the secondary would come on. Now, the secondary just wont come on with A/C on, or hitting the temp (228* I think), but does come on when I jump the pins.
It got warm in traffic, but almost did what it was supposed to do. Primary did'nt kick on, but secondary took over from about 230 and took it down to 215. That's when I first checked, and found the primary did not work.
It can't be a fuse, because when I jumped pins a and b, both fans turned on. Before I replaced the primary, only the secondary would come on. Now, the secondary just wont come on with A/C on, or hitting the temp (228* I think), but does come on when I jump the pins.
Last edited by shribe; Oct 24, 2004 at 01:53 AM.
Melting Slicks
Joined: May 2004
Posts: 2,524
Likes: 10
From: Lufkin Texas
St. Jude Donor '05-'06
Ok I'm pretty well confused now. It's the whole "they both run when jumping the aldl pins a to b" that make me know the fans/relays/fuse/fusible links are good but why only "one working" when AC is on now??, that should have them both on via the AC high pressure switch?? hmmm, strange! Its almost like an ECM thing, or the command from AC hp switch or temp switch is not being recieved by ECM for one fan, because jumping the pins on aldl proves the ECM output still has the ability to ground the relays and run the fans. I dunno 
Definetly a stickler.
I wrote a tech tip about testing relays and wiring a manual switch that may help you understand things a bit better and help you solve the problem. At least you can wire a manual switch if needed. Here it is. Hope it's at least a little help.
https://www.corvetteforum.com/techti...=282&TopicID=2
Definetly a stickler.I wrote a tech tip about testing relays and wiring a manual switch that may help you understand things a bit better and help you solve the problem. At least you can wire a manual switch if needed. Here it is. Hope it's at least a little help.
https://www.corvetteforum.com/techti...=282&TopicID=2
Thread Starter
Instructor
Joined: Sep 2003
Posts: 169
Likes: 0
From: Pemberton Minnesota
Thanks Dave,
A weird one ain't it. I agree with the ECM thing, but how could have that changed? It allowed the secondary to come on when the primary was inop, but won't tell it to come on now that the primary is working.
The part that really has me confused is the fact that:
When the fan motor was bad, I could swap the plugs at the relay, and the secondary fan would come on hooked to either relay--proved motor was bad on primary.
Now, if it was an ecm problem, Primary fan is running, I swap plugs and plug secondary fan into primary relay, the secondary fan shoud come on because the ecm would think it's plugged into primary fan. It can't tell the difference. I would assume a bad motor, but that's not right, because the secondary will turn on if I jump the pins on the ALDL.
Maybe I'd be better off wiring the secondary to a toggle switch anyway. I'd still have the primary as a safety if the car got warm, and I forgot to turn the toggle switch on.
Very, very strange.
A weird one ain't it. I agree with the ECM thing, but how could have that changed? It allowed the secondary to come on when the primary was inop, but won't tell it to come on now that the primary is working.
The part that really has me confused is the fact that:
When the fan motor was bad, I could swap the plugs at the relay, and the secondary fan would come on hooked to either relay--proved motor was bad on primary.
Now, if it was an ecm problem, Primary fan is running, I swap plugs and plug secondary fan into primary relay, the secondary fan shoud come on because the ecm would think it's plugged into primary fan. It can't tell the difference. I would assume a bad motor, but that's not right, because the secondary will turn on if I jump the pins on the ALDL.
Maybe I'd be better off wiring the secondary to a toggle switch anyway. I'd still have the primary as a safety if the car got warm, and I forgot to turn the toggle switch on.
Very, very strange.
Last edited by shribe; Oct 24, 2004 at 02:54 AM.
Melting Slicks
Joined: May 2004
Posts: 2,524
Likes: 10
From: Lufkin Texas
St. Jude Donor '05-'06
Originally Posted by shribe
Thanks Dave,
Maybe I'd be better off wiring the secondary to a toggle switch anyway. I'd still have the primary as a safety if the car got warm, and I forgot to turn the toggle switch on.
Maybe I'd be better off wiring the secondary to a toggle switch anyway. I'd still have the primary as a safety if the car got warm, and I forgot to turn the toggle switch on.
Yeah, I'd wire a manual regardless as a safegaurd, but definetly if you cant find your trouble. Good luck
