Intermittent blower motor function
Thread Starter
Junior Member
Joined: Jan 2019
Posts: 64
Likes: 3
GLK350
Okay, so it stopped again.
Jumping the positive terminal, to bypass the regulator, causes the blower motor to immediately power on.
Upon disconnecting the jump wire, the motor then immediately dies again.
Turned the car off, and back on. Motor did not engage.
Surely the new regulator isnt isn’t messed up in the same way the old one is, right?
Jumping the positive terminal, to bypass the regulator, causes the blower motor to immediately power on.
Upon disconnecting the jump wire, the motor then immediately dies again.
Turned the car off, and back on. Motor did not engage.
Surely the new regulator isnt isn’t messed up in the same way the old one is, right?
Member
Joined: Aug 2015
Posts: 113
Likes: 25
From: Washington State
2013 GLK 350 4Matic
Okay, so it stopped again.
Jumping the positive terminal, to bypass the regulator, causes the blower motor to immediately power on.
Upon disconnecting the jump wire, the motor then immediately dies again.
Turned the car off, and back on. Motor did not engage.
Surely the new regulator isnt isn’t messed up in the same way the old one is, right?
Jumping the positive terminal, to bypass the regulator, causes the blower motor to immediately power on.
Upon disconnecting the jump wire, the motor then immediately dies again.
Turned the car off, and back on. Motor did not engage.
Surely the new regulator isnt isn’t messed up in the same way the old one is, right?
Thread Starter
Junior Member
Joined: Jan 2019
Posts: 64
Likes: 3
GLK350
Probably not. Sounds like you are missing the signal to the regulator from the HVAC controller/Canbus. If you replaced the regulator, that's the only possibility I can think off. You have eliminated the blower and have a new regulator, but the regulator isn't being told to turn on. That video I linked to shows an example of the signal going to the regulator. You need to get it checked by someone with a scope or MB diagnostics. Doesn't have to be a dealer if you have a good european car shop in your area that has the correct diagnostic equipment to troubleshoot the problem.
spoiler alert!
it was the blower motor. The new one functions flawlessly, where as the old one died completely on Monday.
Thread Starter
Junior Member
Joined: Jan 2019
Posts: 64
Likes: 3
GLK350
Just to re-cap all of this for anyone in the future that may find this in a google search:
the blower motor began failing to start, but would engage if the vehicle was restarted several times.
Placing a multi-meter on the input going into the blower motor regulator indicated 12-13v going in, but 0.00 going out to the blower motor.
That lead me to believe it was the regulator, which I now seems clear it wasn’t.
The regulator would initially pass the full voltage into the blower motor, but 3-5 seconds after supplying the voltage, and upon the blower motor not starting, the regulator output would drop back to 0.00. It turned out that attaching the meter to the output *before* powering on the vehicle was important in my situation.
Jumping the blower motor, and bypassing the regulator did cause it to run, but did not cause it to successfully run once the jump wire was disconnected.
2 days ago, while driving in to work, the motor function quickly deteriorated, going from running full tilt, to stopping completely in about 15 minutes time. The output speed quickly started to decline, as a low whining noise started from under the dashboard.
Since I’d already ordered a blower motor, I went ahead and waited to install that before going down the professional diagnostic route. Installation of a new blower motor seems to have corrected the issue.
Thank you both for your help!
the blower motor began failing to start, but would engage if the vehicle was restarted several times.
Placing a multi-meter on the input going into the blower motor regulator indicated 12-13v going in, but 0.00 going out to the blower motor.
That lead me to believe it was the regulator, which I now seems clear it wasn’t.
The regulator would initially pass the full voltage into the blower motor, but 3-5 seconds after supplying the voltage, and upon the blower motor not starting, the regulator output would drop back to 0.00. It turned out that attaching the meter to the output *before* powering on the vehicle was important in my situation.
Jumping the blower motor, and bypassing the regulator did cause it to run, but did not cause it to successfully run once the jump wire was disconnected.
2 days ago, while driving in to work, the motor function quickly deteriorated, going from running full tilt, to stopping completely in about 15 minutes time. The output speed quickly started to decline, as a low whining noise started from under the dashboard.
Since I’d already ordered a blower motor, I went ahead and waited to install that before going down the professional diagnostic route. Installation of a new blower motor seems to have corrected the issue.
Thank you both for your help!
Super Member
Joined: Mar 2013
Posts: 915
Likes: 185
Yikes:
A bit of a journey but glad you're "back in business."
Just to re-cap all of this for anyone in the future that may find this in a google search:
the blower motor began failing to start, but would engage if the vehicle was restarted several times.
Placing a multi-meter on the input going into the blower motor regulator indicated 12-13v going in, but 0.00 going out to the blower motor.
That lead me to believe it was the regulator, which I now seems clear it wasn’t.
The regulator would initially pass the full voltage into the blower motor, but 3-5 seconds after supplying the voltage, and upon the blower motor not starting, the regulator output would drop back to 0.00. It turned out that attaching the meter to the output *before* powering on the vehicle was important in my situation.
Jumping the blower motor, and bypassing the regulator did cause it to run, but did not cause it to successfully run once the jump wire was disconnected.
2 days ago, while driving in to work, the motor function quickly deteriorated, going from running full tilt, to stopping completely in about 15 minutes time. The output speed quickly started to decline, as a low whining noise started from under the dashboard.
Since I’d already ordered a blower motor, I went ahead and waited to install that before going down the professional diagnostic route. Installation of a new blower motor seems to have corrected the issue.
Thank you both for your help!
the blower motor began failing to start, but would engage if the vehicle was restarted several times.
Placing a multi-meter on the input going into the blower motor regulator indicated 12-13v going in, but 0.00 going out to the blower motor.
That lead me to believe it was the regulator, which I now seems clear it wasn’t.
The regulator would initially pass the full voltage into the blower motor, but 3-5 seconds after supplying the voltage, and upon the blower motor not starting, the regulator output would drop back to 0.00. It turned out that attaching the meter to the output *before* powering on the vehicle was important in my situation.
Jumping the blower motor, and bypassing the regulator did cause it to run, but did not cause it to successfully run once the jump wire was disconnected.
2 days ago, while driving in to work, the motor function quickly deteriorated, going from running full tilt, to stopping completely in about 15 minutes time. The output speed quickly started to decline, as a low whining noise started from under the dashboard.
Since I’d already ordered a blower motor, I went ahead and waited to install that before going down the professional diagnostic route. Installation of a new blower motor seems to have corrected the issue.
Thank you both for your help!
Newbie
Joined: Nov 2022
Posts: 1
Likes: 0
Cls55amg and 2012 c63amgcoupe
sounds like the blower motor had a few dead spots. That would explain why the regulator would send an initial burst of voltage then stop if the motor did not start. Glad you figured it out because my 12 c63 is doing the same thing and I have replaced the regulator already and no dice. Mine also (very rarely) will stop during use, I'm hoping it's the regulator detecting the dead spot in the motor every revolution and decides to cut out power. Buying a fan motor on Monday. Thanks for all the info everyone!
