The blower motor for the HVAC in my truck quit working

Tiny
STEVEDWARDS
  • MEMBER
  • 2002 DODGE RAM
  • V8
  • 2WD
  • AUTOMATIC
  • 13,700 MILES
The blower motor for the HVAC in my truck quit working. It stopped working for short periods a couple of times previously but this time it has been out for about a month this time. It does not work at any speed. Fuse #4 for ignition/blower is not blown.

I've removed the motor from under the dash and checked it for continuity with an ohmmeter. There isn't a short in the motor. When I check the voltage at the 2 wire terminal where the motor connects I read about 11.3 volts. This is true no mater what setting the fan speed dial is on or even if the 4 wire harness to the resistor is disconnected.I hooked the motor up directly to the battery with jumpers and it runs every time without fail.I removed the resistor and checked it for resistance with the ohmmeter.I'm not really sure in what combination to test the four different terminals but I got different readings with different combinations.

There is a small hairline crack in the resistor but I'm not sure this is a problem since I've read that the fan should work on highest speed even if the resistor is faulty.I just can't figure out why the motor runs when connected to the battery but not when connected to the terminals. Even though I am measuring voltage at the terminals. It's not a bad connection from the terminals to the motor because I've used jumpers to test this theory. Is the motor not getting enough voltage from the terminals? Is the resistor bad? Help! It's getting cold in the mornings this time of year!
Wednesday, September 29th, 2010 AT 10:19 PM

4 Replies

Tiny
BLACKOP555
  • MECHANIC
  • 10,371 POSTS
The motor will get battery voltage no matter what with they connector because the resistor controls ground side. It sounds like you have a fuse, relay or blower motor that has failed but to be sure lets run down theses guides which will show us how to fix it. This video shows the job being done on a similar car but the process is the same with diagrams below to show you how on your car.

https://youtu.be/1eau7hCuuJ8

and

https://www.2carpros.com/articles/blower-fan-motor-works-on-high-speed-only

and

https://www.2carpros.com/articles/how-to-check-a-car-fuse

and

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

The fuse and relay location are in the diagrams below. Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.
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Friday, April 23rd, 2021 AT 10:42 AM
Tiny
STEVEDWARDS
  • MEMBER
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Thanks for the help. May be making progress towards a solution. I tried your suggestion and found that the motor was now not working the problem must be intermittent. I got a new blower motor that fixed it. Thank you.
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Friday, April 23rd, 2021 AT 10:42 AM
Tiny
BLACKOP555
  • MECHANIC
  • 10,371 POSTS
Take and hook up your voltmeter to the power side then hit it with a test light. Does light come on and voltage stay high or voltage drop and the meter show voltage still or does it drop?
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Friday, April 23rd, 2021 AT 10:42 AM
Tiny
STEVEDWARDS
  • MEMBER
  • 3 POSTS
I did what you suggested. When I connected the test light the voltage dropped pretty much to zero and the light didn't come on.
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Friday, April 23rd, 2021 AT 10:42 AM

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