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Passenger side cooling Fan

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waupachino

New member
My Passenger side cooling Fan is not coming on. Temp when sitting at idle with AC on got as hot as 241, disconnected the Coolant Temp Sender, still only the drivers side Fan comes on. Ran wires from Passenger side Fan directly to Battery and it comes on fine. What could be the issue? I''m at a loss here.
 


I had the same problem on my 97. Only happened when the ac was on. I'm sorry I'm struggling to remember how i fixed it.

It had something to do with the Ac/fan relay in the engine bay fuse block.

For good measure check the connector from harness to fans it's by the header and gets hot and can melt

Sent from my SM-N920V using Tapatalk
 
The harness appears to be in good shape and intact. I did go to the Junkyard and obtained a few test Relays. Just swapped them in, but haven't tested to see if it worked yet.
 
So the relays didn't solve the problem. I had the original PCM so I swapped it in and that didn't solve the problem. I'm at a loss here on what it could be. Any ideas?

By the way I'm working on a 2000 Grand Prix GTP.
 
waupachino said:
Ran wires from Passenger side Fan directly to Battery and it comes on fine. What could be the issue? I''m at a loss here.
Click to expand...

So you've confirmed that the fan does work when fed 12v. That's good. Next step would be confirming 12v at the plug when the fan is commanded to be on.

Seems stupid, but I have seen something very similar to this on a Vibe in the past. Main fan wasn't working. Confirmed the fan worked with a PowerProbe... cool. Confirmed 12v at the plug... head scratch. Plugged it back in and all was well. (?) Turned out there was just enough corrosion in the plug to break the circuit. The act of wiggling, disconnecting and reconnecting was enough to make contact again. I properly cleaned the contacts, put a dab of dielectric grease in the plug, and as far as I know, it hasn't been a problem since.

Moral of the story: Follow a diagnosis path. You know the fan works. Is the relay getting power? Is there power at the plug when the fan is commanded? Is there a ground signal from the PCM triggering the relay? Does the fan itself have a good ground?


Do you own a DVOM?
 
Unfortunately when it comes to diagnosing wiring issues and broken wires etc... I'm an literate so I may have to pay someone to figure this problem out.
 


So since I pretty much had given up on finding the problem myself, I used a jumper wire from the Black wire at the main Fan harness to the Grey wire and now the passenger side Fan comes on when the drivers side comes on. The AC feels much cooler and the car Temp doesn't creep up in traffic like it would before. I don't know why they don't have both Fans come on all the time anyway.
 
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