A/C Blower stopped blowing - Control Module or Fan?
Thread Starter
Super Member
Joined: Dec 2007
Posts: 980
Likes: 224
2005 S500 Designo
A/C Blower stopped blowing - Control Module or Fan?
My AC blower stopped blowing, fortunately I was able to drive home by pressing the AC off button in intervals - it redirected the air so it pushes from the outside and with highway speeds it brought me home in humane conditions. Tomorrow I need to diagnose and/or fix, lest I die in this heat.
Before it failed I heard a brief grumbling noise from inside the dash/lower dash area, then it quit. Restarting the car got the fan to kick on again, but then it quit again. I would expect a broken fan to give some indication more than 3-5 minutes of grumbling no?
I guess it’s an easy diagnosis - hook up 12V leads to the fan and see if it spins. Is it terrible to remove the blower motor?
[edit]
Found this guy fixing it:
I remember having blower issues before, pulling it apart, putting everything back together, and finding no issue. Maybe the regulator is on the fritz, I’m not sure.
Before it failed I heard a brief grumbling noise from inside the dash/lower dash area, then it quit. Restarting the car got the fan to kick on again, but then it quit again. I would expect a broken fan to give some indication more than 3-5 minutes of grumbling no?
I guess it’s an easy diagnosis - hook up 12V leads to the fan and see if it spins. Is it terrible to remove the blower motor?
[edit]
Found this guy fixing it:
I remember having blower issues before, pulling it apart, putting everything back together, and finding no issue. Maybe the regulator is on the fritz, I’m not sure.
Last edited by Fried Chicken; Aug 16, 2020 at 10:07 PM.
MBWorld Fanatic!
Joined: Dec 2012
Posts: 2,474
Likes: 439
From: Ball Ground, GA (N of Atlanta)
2003 S500 2007 GL450
Easy to remove the blower, easy to test - just unplug the regulator from the blower motor and hook power and ground directly to the blower motor. You will know immediately which has failed. If it is the regulator, you can just leave the power (the wires that did go to the regulator) hooked to the blower, and you will have full speed air movement until you can get a regulator.
Thread Starter
Super Member
Joined: Dec 2007
Posts: 980
Likes: 224
2005 S500 Designo
Easy to remove the blower, easy to test - just unplug the regulator from the blower motor and hook power and ground directly to the blower motor. You will know immediately which has failed. If it is the regulator, you can just leave the power (the wires that did go to the regulator) hooked to the blower, and you will have full speed air movement until you can get a regulator.
Thread Starter
Super Member
Joined: Dec 2007
Posts: 980
Likes: 224
2005 S500 Designo
Just swapped out the regulator with one I’d bought prior - works like a charm.
I hope this new used one I got holds up. It’s not a fun job, and it’s even less fun losing heating/cooling unexpectedly.
I hope this new used one I got holds up. It’s not a fun job, and it’s even less fun losing heating/cooling unexpectedly.
Thread Starter
Super Member
Joined: Dec 2007
Posts: 980
Likes: 224
2005 S500 Designo
Worked for appr. 30 min, now the fan isn't working again.
Fuse is fine. Motor is fine. It's possible the regulator is broken (I got a used one). Now I'm faced with the curse of used parts, I'm not sure what's broken.
[edit]
Found error code 1426 that kept reappearing after clearing. I checked the 40A fuse, it’s fine. It’s also getting 12V. It’s pointing to a bad regulator. I ordered a new one form Rockauto: $112 incl. shipping and tax Mahle/Behr OEM.
Fuse is fine. Motor is fine. It's possible the regulator is broken (I got a used one). Now I'm faced with the curse of used parts, I'm not sure what's broken.
[edit]
Found error code 1426 that kept reappearing after clearing. I checked the 40A fuse, it’s fine. It’s also getting 12V. It’s pointing to a bad regulator. I ordered a new one form Rockauto: $112 incl. shipping and tax Mahle/Behr OEM.
Last edited by Fried Chicken; Aug 20, 2020 at 11:10 PM.
