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Discussion Starter · #1 ·
Since last summer, our 2004 Honda Pilot will overheat ONLY under the following conditions:

1) Hot outside
2) A/C is on
3) Car is not moving much

If the A/C is off, but the car is not moving much, it will not overheat.
If the car is moving and the A/C is on, it will not overheat either.

I decided to do a test yesterday to help diagnose the issue.

1) Idle with no A/C. No fans come on (it was cooler out).
2) Turn on A/C. Condensor fan comes on strong, but radiator fan does not move.
3) Turn off A/C. Condensor fan stays on, but radiator fan starts moving slowly.

From what I've read, the radiator fan should move when the A/C is on, but that is not what I'm seeing. That also could explain the overheating.

So my question is what would cause the above? From my research so far, possibilities are:

1) Bad cooling fan relay?
2) Bad wiring to the cooling fan?
3) Bad cooling fan (bad high speed only?)

Any help would be appreciated since this is not a clear cut thing, and I'm still learning. Had anyone had similar issues with their Pilot?

Thanks,
Marz
 

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The condenser fan and radiator fan should both come on when the A/C compressor is engaged. So the way to test is unplug the fan and build a set of test cables to connect the fan straight to the battery. During the test the fan should be turning full speed. If the fans check out I would suspect the fan relays. They are easily changed and are in the fuse box under the hood.

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I think it might be easier to swap the relays first (assuming they are the same part number) just to see if the incorrect behavior follows the fan or the relay. If the incorrect behavior switches to the A/C fan then it points to a faulty relay. Also check the connections at the radiator fan just to make sure you there aren't any loose wires or signs of corrosion on the wires and electrical contacts. You might even unplug and plug back in the radiator fan connection to make sure everything is seated okay. Just be sure to pull from the connector housing and do not pull on the wires. If the behavior remains the same then doing what greg1c suggested to test the radiator fan sounds like a good idea.

Also how is the radiator coolant level? That might not have anything to do with this issue but it's worth ruling out.

Lastly how high did the temperature gauge get when you ran the vehicle in idle before determining the radiator fan did not turn on?

Good Luck,
Steve
 

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Discussion Starter · #4 ·
I have found some more information as I began to troubleshoot. Step 1 was to check the fuse to the radiator fan, and the 30A fuse was blown. I turned the fans by hand to see, and while the condensor fan was smooth and not wobbly, the radiator fan had some resistance and it was wobbly on the spindle. I suspect the fan is causing resistance and blowing the fuse. I've ordered new fuses and a new radiator fan from Amazon, so will give that a shot. I can also install an intact 30A fuse and see what happens under the hood.

Thanks for the feedback so far...
Marz
 

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It sounds like you've nailed down the culprit. Good luck with replacing the fan . . . hopefully it's an easy fix. Let us know how it goes.

Good Luck,
Steve
 

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Discussion Starter · #6 ·
Well yesterday I replaced the 30A fuse and so far it works. When I push the A/C button, both fans go on. With no a/C on, both fans cycle. The radiator fan does stop much sooner than the condensor one, so I do think there is resistance in there. The new fan will be coming this weekend as insurance in case the fuse blows again.

Thanks,
Jeremy
 

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So did you figure it out? I ask because mine is doing it now. If i tap the fan it comes on and sometimes it does without doing anything so I am lost now I really don't want to change the fan assembly it seems like something I'll have to pay to have fixed that makes me wanna cry cause mechanics see me and think they can screw me over.
 

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Something similar is happening to me except the condenser fan does not come on at all. Have tried replacing both relays and still nothing. Is there a control module that relays information from the temperature sensors or something in between all this?
 

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Something similar is happening to me except the condenser fan does not come on at all. Have tried replacing both relays and still nothing. Is there a control module that relays information from the temperature sensors or something in between all this?
Have you replaced the fuse for the condenser fan?
 
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So did you figure it out? I ask because mine is doing it now. If i tap the fan it comes on and sometimes it does without doing anything so I am lost now I really don't want to change the fan assembly it seems like something I'll have to pay to have fixed that makes me wanna cry cause mechanics see me and think they can screw me over.
After the Pilot has sat off overnight, what happens if you try to spin the fan? Does it rotate fairly slowly and come to a stop quickly? Does it feel like it’s not spinning smoothly?

Have you checked the condition of the fan wire harness and connector?
 

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All the fuses looked ok. Should I just replace them all anyways?
At least check them with a multimeter. Just looking at them, even with good eyes, doesn't always catch every bad one.
 

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After the Pilot has sat off overnight, what happens if you try to spin the fan? Does it rotate fairly slowly and come to a stop quickly? Does it feel like it’s not spinning smoothly?

Have you checked the condition of the fan wire harness and connector?
It sounds great I attached it directly to the battery and it didn't come on unless I thumped it so it's the fan. Already removed will be replaced in the am
 

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At least check them with a multimeter. Just looking at them, even with good eyes, doesn't always catch every bad one.
Do you know the location of the cooling fan control module? We are thinking this could be the culprit. The relays work but there's no signal being sent to them.
 

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Yeah that worked then I hard would sounded like leaves stuck in the ac then all of a sudden ask the air up front stopped. Wth is going on
 

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There might be something jammed in the front blower wheel. Any rodents visit your Pilot recently?

Did you get the radiator fan up and running?
 
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