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Fan won't shut off

Tiny
LORIDEMANN
  • MEMBER
  • 2004 CHEVROLET TRAILBLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 181,000 MILES
The AC/Heater fan won't shut off after vehicle is shut off, 2004 chevy trailblazer, any ideas on what is wrong? We had to disconnect the battery to get the fan to stop running.
Saturday, July 30th, 2011 AT 4:38 AM

6 Replies

Tiny
LORIDEMANN
  • MEMBER
  • 2 POSTS
Thanks guys, it's done and it works. Any ideas of why we go through these so often though? Replaced very same part less than 3 years ago and this part was heat damaged. You could smell the burnt smell on the actual old part after we removed it. Man, you guys are awesome!
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Saturday, July 30th, 2011 AT 9:00 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
More than likely this is a relay that is sticking on, or the control module has shorted.

Basically, the way we need to test this is to go the control module which is under the dash and test if you have voltage coming in and out that is 12 volts even when the key is off. If it is, then this is shorted.

Here are a couple of guides that will help with this:

https://www.2carpros.com/articles/how-to-check-wiring

I am attaching the info below on this, but I suspect the module is the problem.

Please let me know what questions you have.

Thanks
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Monday, March 7th, 2022 AT 4:46 PM
Tiny
LORIDEMANN
  • MEMBER
  • 2 POSTS
Hi! We just came from O'reilles Auto parts, and they said it is the Blower Motor Resistor which we had replaced about 5 years ago and it is bad again, it seems. Can you tell me how to get info on replacing it? My husband will do it, watched the other mechanic do it the first time but can't remember how he got to the part to replace it? Ie. Through the dash but is it the glove box area or driver's side? How do you get to the part?
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Monday, March 7th, 2022 AT 4:46 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
This is the control module that I attached the info on my previous post. Sorry but a resistor is just another name for it.

Thanks for the update and let us know what other info you need. Thanks
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Monday, March 7th, 2022 AT 4:49 PM
Tiny
LORIDEMANN
  • MEMBER
  • 2 POSTS
Thanks guys, it's done, and it works. Any ideas of why we go through these so often though? Replaced very same part less than 3 years ago and this part was heat damaged. You could smell the burnt smell on the actual old part after we removed it. Man, you guys are awesome!
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Monday, March 7th, 2022 AT 4:49 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
The reason they fail is basically the coil in the wiring burns up and you get it shorted, stuck on high, or it just stops working all together. This is why you can smell it.

For it to last 5 years, it not surprising that it failed again. I wouldn't expect this to fail every 5 years but that is not too bad.

I don't think you have a greater issue causing the parts to fail. I think you just have a couple of failed parts.

Let us know what other info you need and thanks for using 2CarPros.
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Monday, March 7th, 2022 AT 4:51 PM

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