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DarekG

Manual HVAC/Blower Motor Issues

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Hey guys,

 

I have an issue I've been chasing for a while now, here's a bit of background. I have a 2001 3.5L SE and at one point last year the HVAC/Blower only blew on the highest setting. A bit of research told me that this was due to the blower motor and/or resistor for the controls.

 

As recommended I ordered both a new blower motor and a new resistor. Just to test it out I put in the new blower motor and it didn't turn on or blow air - So that means it's the resistor.

 

For reference here is the type of resistor I mean.

 

768_ULTRAPOWER%20STANDARD%20MOTOR%20PROD

 

 

Now being a dummy, I didn't know much about these at all. So just to "test" it I plug the resistor into the harness but don't screw it back into the duct. I turn on the Pathfinder and turn the HVAC on and the motor blows for about 5 seconds then shuts off.

 

I start to smell burning.

 

I panic and turn the truck off.... Then I go and feel the resistor... Burned the ever living fskc out of my fingers doing so. Another 10 seconds of Google tells me the resistor is cooled by constant airflow from the blower motor and must be screwed back into the duct. I screw it in, and now the fan blows but only on the first 3 settings, not the 4th setting (which is when it stopped working) and I can visibly see discoloration around the edge of the resistor.

 

My questions are..

  1. I'm guessing I burned the part of the resistor that controls the highest blower settings which is why it doesn't work. Can someone confirm?
  2. Is it normal for these resistors to get so damned hot? It instantly seared my skin on contact and started smoking. (Lesson learned.)
  3. I've heard of some "aftermarket" blower motors "pulling too much current" - Is this even possible considering I have the proper fuse in place?

 

I'm gonna order another resistor I guess, but, is it normal for these to get as hot as fire?

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I don't have a particular answer for ya, but I agree, it is definitely concerning that it would get hot so quickly. I doubt it's cooled enough to keep that much heat down...imagine how hot it would get after running climate control for 30 minutes! But maybe Nissan's cooling for it is really clever, who knows. Hope ya figure this out, as I have some acute problems with my HVAC system as well.

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I know the blower resistors in the WDs get hot enough that they can start fires if the HVAC box is full of leaves and crap. Not surprising yours got hot, but odd that it let the smoke out that quickly. Blower motor spins freely?

And yes, if a resistor burned out, that'll prevent power from reaching the motor on that speed. (If it's set up to use the resistors in series, one smoked one could take out multiple speeds.) Basically the resistor module has a few different resistors in it and the HVAC can send power through any of them to the blower motor. Send power through a high-ohm resistor and the blower turns slowly; send power through a low-ohm resistor and the blower spins faster. Max speed should bypass the resistors entirely, though I don't know that for sure on the R50.

Hope your fingers are alright. I was reminded once that everything's a fuse at some amperage when I vaporized a paper clip while holding it with my fingers. That one took a while to heal.

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I've been driving it for a few weeks with the blower going and no issues, so I can basically confirm that it's normal for it to get searing hot but it needs to be screwed back into the air duct before you decide to "test" it.

 

It's odd because now the highest speed (Which is supposed to bypass the resistor completely) is the only one that doesn't work now. I thought maybe I blew a fuse but both 15A blower motor fuses were fine. I'll test with a new resistor to confirm it myself.

 

 

As for my fingers, I've gone "Men in Black" on some fingers and that thumbprint no longer unlocks my iPhone. :laugh:

 

 

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First step to electrical work is to buy a multi meter. You could test for voltage at the blower on hi setting, then work your way back until you find voltage. Then you would know which component was fried.

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