Since my resistor blew, should I replace my blower motor?

dylansalrin

dylansalrin

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My resistor blew a month back and I know what the means and all so I won't start another thread on that, but what I'm asking is should I assume that my motor is bad due to age and corrosion and constant use in the Midwest? I don't want to buy another resistor and have it blow out in a couple weeks again. Should I replace the entire blower motor? I don't have AC. Am I damaging my jeep by using the heat on the highest setting with the resistor blown?
 
That wouldn't be a bad idea at all. My theory is that the resistor packs, wiring, switches etc. start going bad when the motor starts going bad. Windings in the motor are coated with shellac as insulation and as the thin layer of shellac ages, the windings start shorting to the motor starts drawing a lot more current which starts taking components that control the motor out with it.
 
Ok. I know you have a ton on experience with this (I saw posts with you in them from 2009 and 2011) what if I never replaced it? Since my heat does work on high (due to it bypassing the resistor). But if the problem WAS my fan motor then it would eventually burn through the insulation right?


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dylansalrin said:
My resistor blew a month back and I know what the means and all so I won't start another thread on that, but what I'm asking is should I assume that my motor is bad due to age and corrosion and constant use in the Midwest? I don't want to buy another resistor and have it blow out in a couple weeks again. Should I replace the entire blower motor? I don't have AC. Am I damaging my jeep by using the heat on the highest setting with the resistor blown?
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I wouldn't unless it's weak or not producing the airflow it used to. You won't hurt anything running with the blower motor resistor pack bad. The high setting on the blower doesn't use a resistor in the circuit and therefore receives the full 12v from the battery.
 
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BretStep said:
I wouldn't unless it's weak or not producing the airflow it used to. You won't hurt anything running with the blower motor resistor pack bad. The high setting on the blower doesn't use a resistor in the circuit and therefore receives the full 12v from the battery.
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If the fan motor is going bad, it draws more current than it should which is likely why the resistor pack burned out. Running it on high when it is drawing more current than it should (which it does as it ages) is a good way to next start taking out (melting) the wiring and fan speed switch. Which is what happened on my previous TJ, I spent half the day replacing melted wiring and a burned fan speed switch after the resistor pack failed.
 
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I see. Well maybe I replace the resistor and put an inline fuse in to save me a headache lol appreciate the info!


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dylansalrin said:
I see. Well maybe I replace the resistor and put an inline fuse in to save me a headache lol appreciate the info!
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Replacing the resistor and adding a fuse won't fix the problem of the motor drawing too much current for the wiring.

Just to run, a bad motor is drawing more current than the components in the circuit can handle. Fusing it with a big enough fuse so the motor, which is now drawing too much current when running, will run and not blow the fuse will still overheat the wiring and switch.
 
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Jerry Bransford said:
Replacing the resistor and adding a fuse won't fix the problem of the motor drawing too much current for the wiring.

Just to run the motor is drawing more current than the components in the circuit can handle. Fusing it with a big enough fuse so the motor, which is now drawing too much current when running, will run and not blow the fuse will still overheat the wiring and switch.
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Ok. I'm looking at fan motors and they range in price. $170 on quadratec to $40 on rock auto. Does quality matter?
 
dylansalrin said:
Ok. I'm looking at fan motors and they range in price. $170 on quadratec to $40 on rock auto. Does quality matter?
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Yes quality matters but understand Quadratec's prices are generally sky-high and much higher than other sources like from Amazon.com, Rock Auto, etc. The very last place I would buy replacement parts from would be Quadratec.
 
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Jerry Bransford said:
If the fan motor is going bad, it draws more current than it should which is likely why the resistor pack burned out. Running it on high when it is drawing more current than it should (which it does as it ages) is a good way to next start taking out (melting) the wiring and fan speed switch. Which is what happened on my previous TJ, I spent half the day replacing melted wiring and a burned fan speed switch after the resistor pack failed.
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Not necessarily. If you had melted wiring then a short developed somewhere. Otherwise the fuse would have blown to protect the circuit wiring.
 
BretStep said:
Not necessarily. If you had melted wiring then a short developed somewhere. Otherwise the fuse would have blown to protect the circuit wiring.
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Sheesh. Again, as explained three times above, the hvac fan motor windings start shorting together as the shellac insulation wears through. That causes excessive current to be drawn by the motor. So yes there is a short causing things to melt or burn up and it is inside the motor.

This is a common problem fixed by replacing the motor.
 
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