Weird vibration when I turn the fan on

izshadow

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I have a 2007 trailblazer and just recently started to have an odd vibration, like a horrible seat massage haha. Bascially what is happening is when I turn on the fan, while my car is in drive and stopped, it vibrates. If the AC is on, it vibrates, if the AC is off and just the fan is on, it vibrates. If the air circulation is set to circulate from in the suv, it vibrates but as soon as I turn the fan off, it stops. Or if the fan is on (not AC, just fan) and I turn it to circulate from the outside, no vibration. All other times, vibration.

I called an area shop and the owner said he used to own a trailblazer and knows exactly what I'm talking about and he was never able to figure it out before he gave up and sold it.

I did have the engine mounts replaced earlier this year. Though this started afterwards. About a month later this new issue came up. No change in idle when we are stopped, just vibrates. I really hope I explained it good enough. Its not the AC compresser cause it does this when the AC is turned off. Like I said, it does it with the AC on, with the AC off but just the fan on and with it doing the interior circulation. When the AC is on, it doesnt matter if its pulling air from the inside or outside. That only matters when its the fan only. And I only feel it when in drive and stopped at a stop light or stop sign type situation.
 

zora

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Did you check the HVAC fan and motor to see if they are the source of the vibration?
Did you see all the online videos and posts about the same issue?
This is one example.
 

izshadow

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There is no rattle. No noise or anything. Just the vibration when I turn it on. My mechanic was stumped and asked me to post in the forum with ideas. Someone suggested the blower motor so I guess we can look at that. Orginally he thought the raditor motor but it wouldnt make sense and I dont want to just keep replacing parts till its right, I am not a mechanic so just trying to narrow it down to save me money. Is the HVAC fan the blower motor?
 

zora

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There is no rattle. No noise or anything. Just the vibration when I turn it on. My mechanic was stumped and asked me to post in the forum with ideas. Someone suggested the blower motor so I guess we can look at that. Orginally he thought the raditor motor but it wouldnt make sense and I dont want to just keep replacing parts till its right, I am not a mechanic so just trying to narrow it down to save me money. Is the HVAC fan the blower motor?
Yes the HVAC fan is the blower motor.
Did you read the link I provided above?
Did your mechanic actually turn on the fan and feel the vibration?
 

izshadow

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I only saw a quick question and answer which is why I had said no rattle. I didnt see any videos or other articles attached to it. Wonder if I need to sign up to that site to see? And the guy I was going to did. He wasnt sure what it was either and had mentioned he thinks it was my raditor fan motor but neither of us were sure so thats why I ended up here instead of driving shop to shop to find answers. I'm going to message him tomorrow and make a time to get the blower motor looked at! :)
 

zora

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You are saying no mechanic has actually spent time looking at it?
 

izshadow

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I said my mechanic did look and he was going to start with the raditor motor but he wasnt sure what was causing the vibration and it could be a list of things so before we started replacing parts that didnt need replacing to come here and ask so we have a better starting point. And now we do.
 

zora

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turning on the ventilation fan, AC off, has nothing to do with the radiator fan motor.
how skilled is your mechanic?
is he ASE certified?
 
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