R 129 Faulty cabin fan motor - New resistor pack required ?

[Pcn1]

Last year my R 129 developed a faulty cabin blower fan problem.
Basically it ran fin for while then stopped. When the car was turned off and cooled down it then worked ok again. This has happened a few times, and my google research has suggested the most likely culprit is a faulty resistor pack (or Rheostat) mounted on top of the blower motor itself. Apparently these can fail completely or break down intermittently, as in my suspected case.

So following a YouTube video (although its for a 500 and the layout is slightly different) I'm in the process of removing this item for replacement. So while its apart, is there anything else I should check or replace ? I read motor brushes can sometimes be a problem so replace those too ?
Lastly is this resistor still a MB stocked spare part item, or aftermarket only now ?

Thanks

 

[DrNick]

I’d look to change brushes as well if possible. Getting them might be an issue. I’ve had to file brushes down in the past to dodge them in.
If the resistor still behaves then you could measure it’s resistance and get a high wattage one from RS or Farnell. Of course the old ones may just need resoldering.
Be interesting to hear how you get on. Mine might be going the same way.

 

[Pcn1]

Finally got the resistor out as such, still attached to top fan housing/heatsink, but its all expoxed up and cant see any screws that hold it to the heat sink. Looks like it needs to be broken open to reveal fixing screws ?
I'll speak to local MB parts guys tommorow about replacement options.
Motor brushes all look fine.

 

[Pcn1]

Called my local MB parts guys, the only part they used to offer was the whole assembly of top half fan cover with heat sink and resistor pack at £500+.
But its no longer available so that's a non runner anyway.

So its to the aftermarket now, I've booked marked a resistor on e-bay for £35, but can anyone chime in with a recommendation of where else to go for this part ?

 

[Pcn1]

Ive reasembled the basic motor and fan and test run for 1 hour at varoius speeds. Using infared heat gun I coudnt detect any overheating on motor or resistor pack or fuse etc. It ran fine.
My resistor unit is rectangular shape and not the same as the aftermarket units which would mean breaking the old one off and drilling tapping new fixing holes. Think my unit is a Behr ?
And I tend to trust the original parts over a cheap copys from china, unless I know its defo failed and I have no choice but to replace.
So Im just going to reassemble the whole thing and drive the car and see if it returns. If it fails again then at least I know how to strip it down quicker next time !

 

[ray_hennig]

Can't you find the MB part number and then cross-refer that to a reputable aftermarket equivalent?

RayH

 

[Pcn1]

There's no part number on my unit. I may continue to scan the net in case there are new old stock parts still out there.

 

[optimusprime]

SL SHOP .. Just send for parts for my engine from there .