A/C fan motor not running?

Tiny
DEETRA
  • MEMBER
  • 2007 MERCEDES BENZ GL450
  • 4.5L
  • V8
  • 4WD
  • AUTOMATIC
  • 250,000 MILES
Changed the motor, fuse, and fan control panel and motor still doesn’t work, can’t find where resistor is located what else could it be? Was working just fine last week.
Sunday, April 20th, 2025 AT 10:51 AM

3 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,615 POSTS
The blower motor resistor is made into the blower motor. Did the blower motor have more than 2 wires? If it has 6 wires, then you know the resistor is built in. I would check for power and ground at the blower motor with the system on.

Here is a guide to show you what I am talking about:

https://www.2carpros.com/articles/how-to-test-an-automotive-hvac-system-blower-fan-motor-a-detailed

If there is no power to the red wire, please check the #91 fuse in the fuse panel behind the right front seat. The brown wire is ground. Check out the images (below). Let us know how it goes.
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Monday, April 21st, 2025 AT 11:15 AM
Tiny
DEETRA
  • MEMBER
  • 3 POSTS
Yes sir that was the first thing I checked the fuse underneath the passenger seat and it was blown also had already changed it out but the motor still didn’t work, so I changed out the motor and that also didn’t work then I proceeded to change out the A/C fan control panel also didn’t work. I really don’t know what else it could be. If there is any other thing you can think of, please let me know. It would be greatly appreciated, thanks so much!
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Monday, April 21st, 2025 AT 11:47 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,615 POSTS
Can you confirm the blower motor is getting power and ground? Also, since the fuse was blown, I would check the electrical connectors. You should have power to the red wire with the system on?

Please go over this guide:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Let us know how it goes.
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Tuesday, April 22nd, 2025 AT 10:16 AM

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