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Need help diagnosing cooling fan problem

Old Mar 25, 2011
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Need help diagnosing cooling fan problem

Hey guys, I have a 2005 EX Coupe and i've been having overheating problems related to the cooling fan.

It does not turn on at all. I do not have the factory manual, so I don't know what fuses to check.

Can somebody kindly post a fuse diagram and some advice on how to properly troubleshoot this problem?

I want to nip in this in the butt before it starts to warm up down here in Cali.
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Old Mar 25, 2011
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Re: Need help diagnosing cooling fan problem

Just check for burnt fuses.

It's either your fan switch or your fan. Try bypassing the switch with wires directly from the fan to the battery to see if it's a bad fan. If not then it's probably the switch.
I cannot remember if there is a relay also. If there is, then switch it with another relay to see if it's bad (while the car is hot and the fans should be kicking on)

Last edited by Mad Dog Tannen; Mar 25, 2011 at 08:40 PM.
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Old Mar 25, 2011
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Re: Need help diagnosing cooling fan problem

Well I finally had a chance to take a closer look at it.

I noticed that the fans DO turn on when I run the A/C, but not under normal operation and when the motor is hot, WITHOUT the A/C.

I swapped the relays, still no dice.

Is there a temperature-controlled switch in the car? I assume this is the weak link. If so, where can I find it and what does it look like?
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Old Mar 26, 2011
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Re: Need help diagnosing cooling fan problem

It should be right on the hot side where the rad hose connects to the engine, it kinda looks like a 02 sensor from the outside.
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Old May 19, 2014
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Re: Need help diagnosing cooling fan problem

Having the exact same problem as BiggSean, 2002 engine over heating, but cooling fan is not coming on. Fans come on when I turn on the AC. I think the relays are ok (tested by swapping each one into the horn slot and checking to see if the horn still worked). Guessing it is the fan switch, or temperature gauge. Any help greatly appreciated. Couldn't locate the switch Mad Dog Tannen mentioned. Pics?

Thanks all!
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Old May 20, 2014
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Re: Need help diagnosing cooling fan problem

Originally Posted by 7thgensurvivor
Having the exact same problem as BiggSean, 2002 engine over heating, but cooling fan is not coming on. Fans come on when I turn on the AC. I think the relays are ok (tested by swapping each one into the horn slot and checking to see if the horn still worked). Guessing it is the fan switch, or temperature gauge. Any help greatly appreciated. Couldn't locate the switch Mad Dog Tannen mentioned. Pics?

Thanks all!
If you are overheating, you had better make sure the radiator itself is completely full of antifreeze.
(Just because you have a problem and it's a 7th gen, you probably need a head gasket job, if not more. )


The radiator fan switch is in the thermostat housing.




Disconnect the wires from the switch, turn the ignition key to ON ( engine not running) and use a short wire or paper clip to bridge the terminals in the harness connector. Fans should come on if relays and wiring are good.
This checks everything EXCEPT the temperature switch.

HTH
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