2002 Dodge Ram blower motor not 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!
Do you
have the same problem?
Yes
No
Wednesday, September 29th, 2010 AT 10:19 PM

9 Replies

Tiny
BLACKOP555
  • EXPERT
The motor will get battery voltage no matter what with they connector because the resistor controls ground side.

First thing to do is use a jumper from the + side where you get voltage on the motor then take the ground side of the motor and ground it. Does it work? If so the power side is good and well start working on the ground side. If that doesnt make motor turn then there is a issue probably high resistance in the power side to blower.

Let me know
Was this
answer
helpful?
Yes
No
Wednesday, September 29th, 2010 AT 10:44 PM
Tiny
STEVEDWARDS
  • MEMBER
Thanks for the help. May be making progress towards a solution. I tried your suggestion and found that the motor still did not turn when I connected one side of the motor to ground and the other to the "hot" side of the two wire terminal. I used a nearby bolt head for ground and verified it by checking that I still measured voltage from the terminal. What next?
Was this
answer
helpful?
Yes
No
+2
Thursday, September 30th, 2010 AT 3:11 PM
Tiny
BLACKOP555
  • EXPERT
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?
Was this
answer
helpful?
Yes
No
Thursday, September 30th, 2010 AT 9:41 PM
Tiny
STEVEDWARDS
  • MEMBER
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.
Was this
answer
helpful?
Yes
No
Monday, October 4th, 2010 AT 9:06 AM
Tiny
BLACKOP555
  • EXPERT
AHHHHH perfect! Now that it dropped to zero it tells me there is high resistance in the power wire from where your testing it all the way back to where it originates in fuse box or the wire is internally damaged and only barely making contact or that the fuse panel socket itself is corroded down inside where the fuse goes.
Was this
answer
helpful?
Yes
No
-1
Monday, October 4th, 2010 AT 8:58 PM
Tiny
STEVEDWARDS
  • MEMBER
I'll check the fuse and it's connection again but I think they are ok. For my truck the fuse description is for ignition/blower so woudn't I be having ignition problems too if that were the case? Could it be the swich? The voltage I measure doesn't change when I put the switch in different positions.

Thanks for all of your help!
Was this
answer
helpful?
Yes
No
Tuesday, October 5th, 2010 AT 8:50 AM
Tiny
BLACKOP555
  • EXPERT
Ok then you would have problem. Didnt see a diagram for yours. I would be suspecting the wire from blower and up to its splice. The voltage wouldnt change for each setting as its ground side controlled for the resistor. Gets 12v right from a relay or right from fuse for the blower. I can get you a diagram if you need them
Was this
answer
helpful?
Yes
No
+1
Tuesday, October 5th, 2010 AT 2:35 PM
Tiny
RBURKEY
  • MEMBER
2002 Dodge Ram 4.7L V8 2WD, Manual, 194k miles.
I have same problem as original question and have done troubleshooting as described above: blower motor runs from external 12V; HVAC fuse is fine. However, when I connected the + from the wire harness to motor and grounded the motor negative to the frame, the motor works! So, my problem must be on the return (i.E. Low) side. I had just replaced my resistor bank and none of the connections at the motor or resistor bank feel/look bad. How would you troubleshoot from here (i.E. Where would you look)? Do you suspect the speed selector switch? I've pulled the panel and looked at the back and nothing looked wrong/loose/burnt. Any advice would be greatly appreciated.

I've attached a diagram that I copied from another discussion (claiming to be for 2002 dodge ram - but I really don't know for sure.
Was this
answer
helpful?
Yes
No
Thursday, December 16th, 2010 AT 5:30 AM
Tiny
BLACKOP555
  • EXPERT
Check for continuity from ground of motor harness side to ground on vehicle body. Do theresistances change as speed dial is turned?
Was this
answer
helpful?
Yes
No
Saturday, February 5th, 2011 AT 2:51 AM

Please login or register to post a reply.

Recommended Guides