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One of the rear vent windows in my 06 DGC sxt is starting to act flaky. Haven't trouble shot yet. I'm going to start with the switches because that is the usual and most logical thing to wear out first. Just out of curiosity how difficult is it to replace one of those motors? Is it one of those deals where you have to take the whole inside back of the van apart(I'm being sarcastic)?
 

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I am adding to this thread since I saw another post on the 3rd gen forum that had a fix for these

Rear vent window won't close
http://forum.chryslerminivan.net/showthread.php/5351-Rear-vent-window-won-t-close/page3

vheiner

I have replaced lots of these units! The $65 price tag can be reduced to $6.00 by taking the unit apart and just replacing the motor inside. I purchase mine from Alltronics LLC (http://www.alltronics.com/cgi-bin/ca...gi?item=28M122) for $2.25 + shipping. It is a long shaft RK-370C Mabuchi motor and replaces the OEM motor exactly. The assembly on 2001 and older caravans have to be drilled apart. The 2002 and newer snap apart except for two melted tabs that need to be drilled. Anyone with a little fix-it sense can fix these things easily for only a few dollars. It is almost always the motor that goes bad as they are very cheaply made. I can remove the motor assembly from the van, replace the motor in it and put it back in the car usually in less that 15 minutes so it isn't a difficult thing to do. I have yet to have one not work afterward.
 

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I can verify that this does work. I bought a couple RK-370C motors from Alltronics, with the 17mm long shaft, and they were an exact replacement for the motors inside the rear vent servo assemblies, down to the dimensions, screw hole positions, and terminal lug types. You can find these motors on Alltronics' web site, where there is a $20 minimum purchase plus shipping, or on Alltronics' eBay store, where the cost per motor is higher but there is no minimum purchase.

I drilled out the plastic "rivets" holding the servo assembly cases together, and reassembled using screws (in my case, just little sheetmetal screws that I had on hand).

I tore apart one of the defective motors, and found something interesting. The brushes were still in good shape, and the bearings were fine. The commutator did not appear to be contaminated, but that's of course hard to quantify visually.

So, it could potentially be contamination of the brushes/commutator, causing only part of the windings to be properly energized.

However, the motor's permanent magnet, a continuous cylindrical magnet, was loose and could be rotated by hand within the motor's housing. My hypothesis is that the rotational magnetic force combined with vibration could cause the magnet to slip and no longer be properly aligned with the positions of the brushes. If it slips enough, it could cause the motor to operate backwards, something I've observed happening on these motors (when they fail, eventually they stop running, and then if jiggled enough, they start running backwards, where pushing the vent switch to the Open position makes the motor close the window, and vice versa).

- G
 

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This thread reminded me of a video I saw from Eric the Car Guy about a year ago. He takes the motors out of a 98, the procedure should be exactly the same, and restores the motors without replacing them.

 

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This thread reminded me of a video I saw from Eric the Car Guy about a year ago. He takes the motors out of a 98, the procedure should be exactly the same, and restores the motors without replacing them.

On the flip side I've read a couple of times people trying this and it only lasts a few weeks or months. Course that's not to say it can't be a permanent fix.
 

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On the flip side I've read a couple of times people trying this and it only lasts a few weeks or months. Course that's not to say it can't be a permanent fix.
+1. If my hypothesis is correct, and the problem is that the permanent magnet is slipping inside the case, taking the motor apart and putting it back together may get it working, purely by virtue of aligning the magnet and brushes differently, but the problem will soon recur.

For example, Eric the Car Guy doesn't mark the crucial relationship between the back plate and the housing on the motor, and when he reassembles it, the plate is aligned differently from what it was when he took it apart (look closely, and watch the relationship of the red dot to the label between when he disassembles it and when he reassembles it the 2nd time). The relationship between the brush locations and magnetic N/S pole locations is critical to the motor's operation (and direction of spin).

As I mentioned the permanent magnet in the RK-370C motor I tore apart was not snug in the case - I could rotate it (with just a little drag) just by inserting my thumb into the motor and turning the casing. Remember that the rotational force exerted on the shaft is equal to the rotational force exerted on the magnet.

Try it - take one of these apart, and run the motor using a 9V battery without the casing: just the magnet, armature, and brushes/backplate. As it runs, rotate the magnet. You'll see the motor slow down, stumble, stop, and then reverse direction, as you rotate the magnet relative to the back plate.

- G
 
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For example, Eric the Car Guy doesn't mark the crucial relationship between the back plate and the housing on the motor
I should correct this -- on the first motor Eric does, he does not mark the relationship and assembles it the second time with a different alignment. On the second motor, later in the video he does show marking it in order to make the screw hole line up.

- G
 
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A few more observations:

1. I have been able to reproduce my hypothesized mechanism -- the permanent magnet rotates in the housing, causing the motor to fail. I marked the magnet, ran the motor several times, and soon it stopped running. On re-opening the case, the magnet had shifted.

2. This happens more easily when the motor is cold.

So, perhaps a repair of a failed RK-370C motor would involve re-aligning the magnet and then locking it in place using some flexible adhesive or a tiny drilled hole and screw (in a location compatible with the window servo housing).

- G
 
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