Early W210 Blower Motor Regulator Replacement DIY Here...
For those who have a weak A/C blower that does not seem to change speed despite where you set the controls, here is a DIY to replace your Blower Motor Regulator.
At some point in the run of the W210, Mercedes-Benz decided to redesign the unreliable regulator. Unfortunately, the redesign included the entire blower assembly, so if you try to buy a replacement for the regulator from your dealer you will be sold a new blower assembly, a new housing, and the new regulator.
However, a former local wrench in the Atlanta area described adapting the blower motor regulator from a W140 (S-Class) to the early W210 (The later W210 has a totally redesigned part and only a new regulator is required if your part fails). Here is my interpretation of the adaptation:
First of all lets see where the part is located. Look under the passenger side footwell and look up. This is what you will see: http://www.bimmerboard.com/members/i...l/IMG_0900.JPG
Remove two phillips head screws and the cover can be pulled off toward the seat. With that cover off you will see the blower motor cover: http://www.bimmerboard.com/members/i...l/IMG_0871.JPG
Remove the five Torx screws(T-20 i believe) and you will expose the blower motor and harness near the corner to your right nearest you: http://www.bimmerboard.com/members/i...l/IMG_0895.JPG
Disconnect the harness by pulling apart. There was no locking mechanism that I could find. After releasing the harness, remove four torx screws(Same size as the cover) and the blower assembly will drop down. If you look up the void left by dropping the blower you will see your A/C filters. Check their condition and replace them if they look dirty at all. I had replaced mine recently and they still looked new: http://www.bimmerboard.com/members/i...l/IMG_0891.JPG
Take you blower assembly to your work table and you will see the blower motor regulator attached to the blower motor with two torx screws of the same size as all the others you removed earlier. Here is a picture of the old and new regulators. I purchased mine from http://www.autohausaz.com/ http://www.bimmerboard.com/members/i...l/IMG_0874.JPG
Remove the two torx screws and cut your OLD harness right next to the OLD regulator. You will be cutting four wires: a thick black one, a thick blue one, and two thinner yellow and red ones: http://www.bimmerboard.com/members/i...l/IMG_0881.JPG
I stripped most of the black sheath covering the three wires on the OLD harness to give myself room to strip the insulation off of the three wires I will need to splice.
Next take your new harness and regulator. You can go ahead and connect the blue wire with the spade connector to the blower motor. You will need to remove the blue wire coming from the OLD harness from the motor to do this. Throw the old blue wire away. The OLD red wire attached to the blower motor will stay. This is what it will look like: http://www.bimmerboard.com/members/i...l/IMG_0883.JPG
Now cut the four wires going into the NEW harness connector(Cut the wires as far away from the new regulator as possible). Note that the blue one goes straight to the blower motor so it will not be cut. You will need to cut right next to the connector box in order to leave enough wire to splice to the OLD harness. When you cut the four wires, you can discard the thick red wire. The other three wires will be spliced to the three wires (black,yellow and red) from the OLD harness. Here's how i spliced and soddered mine: http://www.bimmerboard.com/members/i...l/IMG_0886.JPG
I then taped each wire with electrical tape, put a very thin coat of the included dielectric grease to the new regulator, and mounted the new regulator with the two new torx screws supplied with the new harness: http://www.bimmerboard.com/members/i...l/IMG_0888.JPG
I then installed it under the dash in reverse order and started the car up. Woo hoo! It worked. Lots of $$$ saved.
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I have a 'no blower' situation as well. I have a W210 E300TD (Jan 98) which I assume will have the older blower/regulator assembly. (It's done well to be fair. I've had it from new and it's done 193,000 miles).
This may not be relevant however the issue seemed to start after my A/C was re-gassed and then had to have a 'sealant' injected to try to fix a suspected A/C leak.
What I'm confused about is if mine is the old assembly blower do I need to buy the S Class regulator that you mention and then adapt the cabling or do I buy the newer E Class regulator and adapt the cabling?
I've replied to your PM. The only reason you would buy the updated parts would be if you know that your actual blower motor is not functioning. The most common issue is that only the regulator has failed in which case all you need is the old style W140 (S-CLass) regulator that you will adapt to your car.
thought about doing one myself after all the research i’ve done on this fix… i didn’t really find a detailed "how-to" with pictures (although a couple of members claimed they would do one)… so i had plans to do it when my part arrives… now i won’t have too…
i tore my regulator out last week to test it and discovered it’s only putting out 3.2 volts… working spec should be at 0.8 volts low to 6.0 volts high… and you can’t fix the regulator… do to it being a “potted” module (sealed components)… the only fix is to replace the thing and your instructions do the job…
like you… i searched the web and found autohausaz.com to be the lowest priced supplier (and i must say excellent service) with two manufacturers: Kaehler (KAE) #1408218351 at $163.63 and Behr # 1408218451 at $214.79...
i ordered the more expensive unit by Behr (Germany) because i was told the less expensive version from KAE is made in France and does not hold up as well… although… i do believe they may have since modified the heat sink from the original version (notice it’s thicker) and even they’re model works better then what was originally used in the E-class… (which i believe they supplied as well).
anyhow… great job… this fix should be of use to a lot of people… since it’s a common problem…
my boss noticed what i was doing and asked if i would check his ‘97 E320... and i found it to be weak as well… it’s the same as mine… only 3 volts… blowing at half speed even though the controller say's max... looks like i’ll be doing two conversions.
I'm glad it helped. Interstingly enough, the first sign of anything going wrong with my regulator was that there was no difference between the highest setting on the fan control and the setting just below it. This went on for about six or eight months, until I was finally left with what seemed to be the lowest fan speed despite the control panel showing the highest speed.
Yeah, talked with an electrical tech at work… he said solder is best of course… but an insulated crimp-on connector, installed properly should work ok as well… recommended using some electrical tape over the connections after assembled to assure they don’t come apart or get loose over time… should work fine for this installation…
i did the modification on mine yesterday kind of as Tony suggested… soldered the wires and then heat shrink tubing to insulate… wrapped it all up with some electrical tape and reinstalled...
now it blow’s like mad… we realized it had only been working up to three bars… (anything displayed beyond that showed no change in actual fan speed) now at four, five, six bars it progressively gets faster and seven well, it will blow your hat off… well almost… he he he…
it’s a great fix… scheduled to do a friends on Thursday for him… and i’ll try to take some pictures of the results…
Tony's Blower motor regulator fix was awesome. I followed his procedure and it worked perfectly. This save a person about 600 dollars easy. It will be very easy to do for the mechanically inclined person. Do not buy the new unit for 800 dollars. Use this procedure and you will be very happy. Thanks Tony
I removed my blower today and ordered the parts from Autohaus. It took me about 20 minutes to remove, thanks to your instructions. I will post after the installation. I am sure I will have success soon!
Hello. David here from Ireland. read your description of how to adapt in the S-Class regulator. Very Impressive. Well, it's the same story here in Ireland, Mercedes made a crappy blower regulator, but here they are charging 1100 EUROS for the revised parts you must get. So I said I'd go along with your plan. The only worry I have tho' is that in the Irish models there's a different regulator for the A/C E-Class and the Climate Control E-Class and the Automatic Climate Control E-Class. In the forum, ye don't mention any of these. Does it not matter or do ye all have Auto Dual Climate Control in the US (the controls that have a digital LCD screen and an auto button and 2blue and 2red temperature buttons for each side of the car). That's the system I have. If I knew the S-Class regulator would work on that system, I'd go away and order that very one off AutoHaus.
Mercedes Ireland tell me that there's 3 different S-Class regulators and they won't tell me if they are 3-wire or 4-wire and they cost more anyway. My regulator looks like yours, but different numbers and the fan is totally different.
just fixed my regulator via the directions given. worked perfectly
thanks very much for the info.
also went to change th cabin filters, but couldnt get the glove box out, took out all 6 screws ond the screw holding the latch ( 7 altogether ) and it still wouldnt come out, anyone know why
David: I believe all the US spec E-class models have the dual digital temperature control climate control unit. That said, it would be unusual for M-B to have had different blower motor regulators for the same model at the same time, so I believe if you have an early W210 this adaptation should work.
Harbcon: When I replaced my cabin filters, I remember that once I had all the screws removed it took a large amount of force to pull the glovebox out. If you are sure that you have removed all the necessary screws go ahead and give it a quick strong jerk and it will make some cracking noises as it comes out. To make sure you have all the screws out, do a search for glovebox removal or A/C filter. I recall that someone described the procedure and posted it on this message board.
Awesome article Tony. Thanks for posting it. My problem sounds a little different. My HVAC system is highly temperamental. Some days it doesn’t blow at all. Some days it only blows at full blast and no amount of button pushing will stop it except to turn it completely off. And some days it will warble fast to slow very rapidly. Do you think replacing the regulator will solve this issue? I’ve lived with it this way for 3 years and with winter coming the idea of not having heat some days is looking less appealing. I have a 1998 E-320 (W-210).
Drives: '97 E420 sport, '89 BMW 735i, '71 '73 BMW 2002, '64 Impala
Awesome write up! I have had my E420 for a year and a half with no fan. There was no way I was gonna give the "stealer" that much of my money. I will be doing this within the next week or so. Again, thanks for posting this.
David, when you say expensive how much are we talking? Has anyone else had any experiences similar to mine? Any alternative fixes out there? I'm really tired of giving the dealer a ton of money when I know I could probably fix it myself.
and here’s a company that can fix the climate control unit for you… if that’s what’s needed… they also have some help pages you might check out or just contact them… if they can help you fix it yourself… they will..!!