My internal fan has served me well, I replaced the brushes and its been going for 180K miles, however it now seems to be running slow or stop, just unpredictable really.

I’ve noticed that if I push the brushes in firmer into the commentator the fan works great, however this perhaps is a not a brush issue as they are still long, but the resistor failing perhaps?

Can anyone tell me what are the symptoms of the resistor failing would be? Long start up time for the motor? Funny speed settings etc?

 

I replaced my regulator way back when because of agonizingly long delays. The motor simply would not turn on when the HVAC fan button was pressed. It started with just a few second delay, worked it's way up to a minute or so. Then two, then it went full diva and only started if it felt like it. And the speed settings were all over the place until it settled down. If your motor acts like mine, the regulator may solve the problem. It's a 20 minute repair involving two wires. If nothing else, pull your regulator and tap it with a hammer. If it get better for a short while, thats it. If it doesn't get better, it may still be the regulator.

Here's a link to my DIY with photos repair - www.fitzhughmedia.com/MBF/acregulator.html
The same repair is also covered on page 64 of the prior edition of the Southwest Star magazine.

 

Thats exactly my problem, the delay has been getting worse to start when turning the fan on.
I will see if I can get another resistor.
PS i've taken the fan out so many times I can change the regulator no problem so this is great !

 

so i tapped the resistor and sure enough it is now working, lets hope it lasts for abit.

 

I had this issue and found the resistor (honeycomb) on ebay el-cheapo but it works fine now.

Cheers

 

Agreed, I bought a complete fan and resistor combined second hand genuine Merc, only to find that the resistor was gone. The ebay seller was good enough to refind my £20 and I then bought a cheap resistor for £14 from ebay and its been working since, so fingers crossed !

 

The new resistor I bought is playing up and works 50% of the time.
Has anyone found that non genuine MB resistors do this?

 

Failures of the Blower Motor Resistor/Regulator have been a very common problem. As a result, MB has upgraded the part several times. Note: The regulator has to dissipate a lot of heat, when fan speeds of less then max are in play, which is most likely the cause of so many failures.

The current genuine MB part is 210 820 62 10, which sells for around US $249.

My factory installed regulator was part # 202 820 73 10. In addition to the MB logo, an additional marking was BEHR (e.g. OEM supplier to MB).

Having read numerous forum posts regarding problems with using eBay and/or knockoff parts (e.g. reliability, fitment etc.), decided to do it right and only once, purchased the current BEHR OEM replacement part. The cost was US $95, shipped. While it was an exact fit, the cast aluminum heat sink was noticeably larger than the original factory part.

This was the same replacement part that MarcusF used in his DIY repair link, shown in post #2 above.

Also see http://www.panchogun.com/FVWebPhotos...bin-Filter.jpg You may need to click on the thumbnail to open full size.

 

Serndipity hit the nail on the head. Here's the picture of the back of a genuine Behr regulator for our cars. It's made that way because the entire back is a giant heat sink.



The last words in the article are "So what does it cost? My Behr regulator cost about $100, but I used a reputable parts supplier. A cheap Ebay knockoff that shorts out the car and burns down the garage may have a slightly higher total cost of ownership."

I can't say what Behrs manufacturing expenses are, but I bet a good chunk of the R&D went into cooling. The cheap knockoffs? It just might be they don't spend so much on cooling R&D. There are knockoffs that "look" like they may cool properly, but I have no idea what their metal is made of (some aluminum alloy or whatever was cheapest in the metal recycler's bin), whether they maximized the heat sink surface area, how much thought went into the shape of the cooling area (pins or fins, straight or flared), did they optimize spacing to get adequate airflow, the attachment method, and a number of other considerations that we as consumers shouldn't have to think about. That's why some go with brand name parts. The brand name companies have allegedly done the research so it's plug it in and forget about it. That's opposed to plug it in and it runs right until it gets hot, and then it does whatever it feels like.

Here's an Ebay W208 regulator. I don't want to say anything bad about the guy's part, because I've never used it . . . . . . but it's $25. Retail. So it costs some manufacturer $4 to build this regulator? I think there's a difference between that part and a Behr part.

 

MarcusF great write up and excellent reminder that saving a few dollars could be costly in the long run. There are some small manufacturers who do a great job (ANZ optics, Top Hydraulics, etc.) in aftermarket replacement/improvement and the forums are an excellent place to identify and leverage them as cost effective alternative.

 

I've sent the ebay one back and told them its crap. From my own experience it is always best to buy genuine for anything to do with electrical parts on MB and if too dear then buy second hand but genuine.

 

Hey guys, need your help!!!!
So my ac/heater blower is working but its not working with the same force it used to. Do I need a new regulator or is it the motor?

Thanks

 

You could first try to clear the cabin filter first, I found a bunch of leaves in there, once cleared my vents roared through !

 

A1ek is correct and the cabin filter is the first part to inspect or replace when these symptoms are inherent.
The porcupine resistor and blower are next diagnosed with an amp gauge on the motor.
If the fan continues to hunt or has hysteresis, the resistor is much cheaper (oem or generic) to replace than the blower motor or the Control head.

 

Nothin' like a good 4 year old BUMP as a first post.

Heater blower motor was squealing pretty good, off and on for a month or so. Wife (her car) didn't tell me about it, and now the fan motor doesn't function at all.

Vehicle is '98 W208, CLK.

Fuse is good.
Haven't pulled the blower motor out yet, so I haven't tested for voltage to the connector (and am not yet familiar with the parts, terminals, etc.)
I did replace the control module last week (several buttons had taken a dump); the blower responded to input, all was good for a week, and the the blower ceased working all together.
Cabin filter has been replaced; it wasn't too bad, no rodents or other small furry creatures.

Can the motor be tested without the relay?
What are the "test points" for the relay, etc.

Is a link available for a wiring diagram.