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HVAC blower motor resistor replacement


Viking Jeeper

Formerly known as "Mike the Silver TJ"
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Jacksonville FL
My blower motor has been working only on the highest setting for a while now. Finally getting around to replacing it. It was not an easy job for me, my hands just dont have the dexterity they used to after surgery on both hands. I have almost everything back in except for the top screw on the resistor (not sure how I'm going to get that screw started). Before more wiggling and cussing I decided to check the blower at this point. It works on settings 3 and 4 but not 1 or 2. Any ideas? Bad new resistor? Is there a way to check them? The old one does not show any signs of overheating or melting.
 

reddvltj

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My blower motor has been working only on the highest setting for a while now. Finally getting around to replacing it. It was not an easy job for me, my hands just dont have the dexterity they used to after surgery on both hands. I have almost everything back in except for the top screw on the resistor (not sure how I'm going to get that screw started). Before more wiggling and cussing I decided to check the blower at this point. It works on settings 3 and 4 but not 1 or 2. Any ideas? Bad new resistor? Is there a way to check them? The old one does not show any signs of overheating or melting.
There's the possibility that your fan switch and or wiring to the switch is bad. When I replaced my blower motor and blower resistor I ended up having to replace the fan switch and the plug ins to the resistor and switch.
 

KillerIsMe

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Aug 30, 2019
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NE Pennsylvania
My blower motor has been working only on the highest setting for a while now. Finally getting around to replacing it. It was not an easy job for me, my hands just dont have the dexterity they used to after surgery on both hands. I have almost everything back in except for the top screw on the resistor (not sure how I'm going to get that screw started). Before more wiggling and cussing I decided to check the blower at this point. It works on settings 3 and 4 but not 1 or 2. Any ideas? Bad new resistor? Is there a way to check them? The old one does not show any signs of overheating or melting.

Not my Jeep but my Honda Fit had the problem with the fan only working on high. At first I replaced the resistor (HUGE pain in the ass) and it worked fine for about a week. Then, same problem. Internet research led to the problem being the motor wearing out (fan bearing) and - no expert here - overloading the resistor. So I replaced both the motor and resistor and have had no issue since (it's been almost a year). If you did the same and replaced both and you're still having problems my inexperienced and unmechanical self would probably think the resistor is not good - perhaps a crap brand or something.
 

Leahatrill

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Toronto
HAHAHHA. This post cracked me up just now. Lol. I’ve had my new resistor hiding somewhere in my Jeep for a whole year now because I don’t feel like squeezing underneath the glovebox area lol been dealing with only the high setting for a year....I may do it tomorrow though after reading this thread
 
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Viking Jeeper

Formerly known as "Mike the Silver TJ"
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Jacksonville FL
HAHAHHA. This post cracked me up just now. Lol. I’ve had my new resistor hiding somewhere in my Jeep for a whole year now because I don’t feel like squeezing underneath the glovebox area lol been dealing with only the high setting for a year....I may do it tomorrow though after reading this thread
It sucked and I still dont have speeds 1 and 2!
 

MountaineerTom

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If you push in on your fan switch while on 1 and 2, will it run then?

 

Viking Jeeper

Formerly known as "Mike the Silver TJ"
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Jacksonville FL
If you push in on your fan switch while on 1 and 2, will it run then?

No. I've switched the stock resistor in and the replacement again. Same results. With stock resistor it only works on 4. With replacement it only works on 3 or 4.
 
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reddvltj

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No. I've switched the stock resistor in and the replacement again. Same results. With stock resistor it only works on 4. With replacement it only works on 3 or 4.
Have you pulled the switch cluster out of the dash and looked at the wiring and back of the switch yet?
 

Viking Jeeper

Formerly known as "Mike the Silver TJ"
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Have you pulled the switch cluster out of the dash and looked at the wiring and back of the switch yet?
That will be tomorrow, ran out of time tonight. So far everything I have ever worked on in my TJ has been in fantastic shape. Yes, it is 15 years old but the POs never messed with anything, it has only 60,000 miles on it, it has been in FL the whole time and garaged most of the time. I will be looking at that but I dont expect to find anything wrong there.
 
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MountaineerTom

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My switch was slightly melted for a couple years before it acted up. It may have been like that before I got it. The first time I took the switch panel out after getting it, I noticed the melting, then it was a couple years later before it acted up.
 
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Wesrj86

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Jun 8, 2019
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Stringer, MS
That will be tomorrow, ran out of time tonight. So far everything I have ever worked on in my TJ has been in fantastic shape. Yes, it is 15 years old but the POs never messed with anything, it has only 60,000 miles on it, it has been in FL the whole time and garaged most of the time. I will be looking at that but I dont expect to find anything wrong there.
Did you ever figure out what your problem was?
 

Zorba

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Merritt Island, Fl
I have yet to personally see one of these resistor packs that keep burning up - the dealership that sold me my TJ changed it out and tossed the bad one. With that said, has anyone thought about rebuilding one with higher wattage resistors? Is it reasonably possible?
 

reddvltj

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.... has anyone thought about rebuilding one with higher wattage resistors? Is it reasonably possible?
The problem with adding more resistance is, the wires are barely adequate for the original resistor and fan motor. In many cases the wiring and switches also suffer from high current draw.
 

Zorba

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The problem with adding more resistance is, the wires are barely adequate for the original resistor and fan motor. In many cases the wiring and switches also suffer from high current draw.
That's not what I'm saying...

You use the same value resistors as stock - just higher wattage rating that won't burn out. Don't know if its feasible as I've never seen the actual part.
 

reddvltj

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That's not what I'm saying...

You use the same value resistors as stock - just higher wattage rating that won't burn out. Don't know if its feasible as I've never seen the actual part.
The resistor pack is the weakest link. If you upgrade the resistors to keep them from burning out the nest weakest link will burn up. I would rather burn out a resistor pack than have a dash fire...

There are 2 different types of resistors,
The old design, coil type
1590441789428.png


And the newer design, solid state.
1590441851544.png


The best way to avoid all of it is to fix the problem in the first place. Which tends to be a blower motor that is pulling too much amperage and causing everything to heat up to the point resistance also increases and something finally gives...