w203 stepper motor wont stop turning (behind radio)
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w203 (c240)
w203 stepper motor wont stop turning (behind radio)
hello,
i have a 2002 c240, the stepper motor behind the radio wont stop turning, i have ripped open the dash and found it, all plastic linkage and gearwheels appear to be in good order, when stepper motor is removed i can hand turn the gears in there proper direction, when car is turning on the stepper motor turn the gear and the starts clicking as it keeps trying to turn, not sure if a bad motor or if they are supposed to keep turning, can try changing setting and doesnt affect it.....
could use some pointers
i have a 2002 c240, the stepper motor behind the radio wont stop turning, i have ripped open the dash and found it, all plastic linkage and gearwheels appear to be in good order, when stepper motor is removed i can hand turn the gears in there proper direction, when car is turning on the stepper motor turn the gear and the starts clicking as it keeps trying to turn, not sure if a bad motor or if they are supposed to keep turning, can try changing setting and doesnt affect it.....
could use some pointers
MBWorld Fanatic!
Joined: Dec 2003
Posts: 3,275
Likes: 236
From: BC, Canada
2003 C230K Coupe Orion Blue
Welcome to the forum.
The HVAC stepper motor problem has been discussed many times here. Please search online before starting a new thread as it just adds to the clutter.
The link you want is below.
W203 HVAC stepper motors, linkages
The plastic gears inside the motor modules are known to fail. If you remove the motor in question and open it up, the problem will be obvious. Personally I've had 2 motors fail so far. In each case it was a tooth snapping off a (different) gear.
Your C240 will have 6 in total. The link above includes a diagram showing the location of all 6. The motors aren't the cheapest, but it all comes down to how many times you want to rip apart half the dash. Motors can be purchased off 3rd party sites for less. The (Behr branded) ones from reputable distributors are the exact same ones from the dealership, minus the shiny box.
They also upgraded some of the plastic linkages. Not sure which if they were all beefed up but at the ones directing air to the feet (both driver and passenger sides, PN 203-830-00-33) have been updated for sure. The original ones are undersized and WILL break. Be sure to change these out too while you have everything apart.
The dealer also sells a kit that contains a bunch of external gears and linkages, PN 203-830-00-32. It wouldn't hurt to replace as many of these gears as possible. Personally I'm not sure how many the dealer actually changed on my car (my initial repair was covered under warranty), but when I opened up my dash a few years later I found bits of some of the round gear pieces.
The HVAC stepper motor problem has been discussed many times here. Please search online before starting a new thread as it just adds to the clutter.
The link you want is below.
W203 HVAC stepper motors, linkages
The plastic gears inside the motor modules are known to fail. If you remove the motor in question and open it up, the problem will be obvious. Personally I've had 2 motors fail so far. In each case it was a tooth snapping off a (different) gear.
Your C240 will have 6 in total. The link above includes a diagram showing the location of all 6. The motors aren't the cheapest, but it all comes down to how many times you want to rip apart half the dash. Motors can be purchased off 3rd party sites for less. The (Behr branded) ones from reputable distributors are the exact same ones from the dealership, minus the shiny box.
They also upgraded some of the plastic linkages. Not sure which if they were all beefed up but at the ones directing air to the feet (both driver and passenger sides, PN 203-830-00-33) have been updated for sure. The original ones are undersized and WILL break. Be sure to change these out too while you have everything apart.
The dealer also sells a kit that contains a bunch of external gears and linkages, PN 203-830-00-32. It wouldn't hurt to replace as many of these gears as possible. Personally I'm not sure how many the dealer actually changed on my car (my initial repair was covered under warranty), but when I opened up my dash a few years later I found bits of some of the round gear pieces.
Last edited by slammer111; May 3, 2020 at 08:33 AM.
Thread Starter
Newbie
Joined: May 2020
Posts: 4
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w203 (c240)
Welcome to the forum.
The HVAC stepper motor problem has been discussed many times here. Please search online before starting a new thread as it just adds to the clutter.
The link you want is below.
W203 HVAC stepper motors, linkages
The plastic gears inside the motor modules are known to fail. If you remove the motor in question and open it up, the problem will be obvious. Personally I've had 2 motors fail so far. In each case it was a tooth snapping off a (different) gear.
Your C240 will have 6 in total. The link above includes a diagram showing the location of all 6. The motors aren't the cheapest, but it all comes down to how many times you want to rip apart half the dash. Motors can be purchased off 3rd party sites for less. The (Behr branded) ones from reputable distributors are the exact same ones from the dealership, minus the shiny box.
They also upgraded some of the plastic linkages. Not sure which if they were all beefed up but at the ones directing air to the feet (both driver and passenger sides, PN 203-830-00-33) have been updated for sure. The original ones are undersized and WILL break. Be sure to change these out too while you have everything apart.
The dealer also sells a kit that contains a bunch of external gears and linkages, PN 203-830-00-32. It wouldn't hurt to replace as many of these gears as possible. Personally I'm not sure how many the dealer actually changed on my car (my initial repair was covered under warranty), but when I opened up my dash a few years later I found bits of some of the round gear pieces.
The HVAC stepper motor problem has been discussed many times here. Please search online before starting a new thread as it just adds to the clutter.
The link you want is below.
W203 HVAC stepper motors, linkages
The plastic gears inside the motor modules are known to fail. If you remove the motor in question and open it up, the problem will be obvious. Personally I've had 2 motors fail so far. In each case it was a tooth snapping off a (different) gear.
Your C240 will have 6 in total. The link above includes a diagram showing the location of all 6. The motors aren't the cheapest, but it all comes down to how many times you want to rip apart half the dash. Motors can be purchased off 3rd party sites for less. The (Behr branded) ones from reputable distributors are the exact same ones from the dealership, minus the shiny box.
They also upgraded some of the plastic linkages. Not sure which if they were all beefed up but at the ones directing air to the feet (both driver and passenger sides, PN 203-830-00-33) have been updated for sure. The original ones are undersized and WILL break. Be sure to change these out too while you have everything apart.
The dealer also sells a kit that contains a bunch of external gears and linkages, PN 203-830-00-32. It wouldn't hurt to replace as many of these gears as possible. Personally I'm not sure how many the dealer actually changed on my car (my initial repair was covered under warranty), but when I opened up my dash a few years later I found bits of some of the round gear pieces.
thank you for your response
i opened it up and didn't see anything super apparent on the gearing, just that it does seem a bit loose and skips easier in one direction more then the other but that was fixed when i snapped it back together, its intresting that when its plugged in it powers up and willl turn the gear but then just keep turning and turning and thats when the clicking starting because its turned the flap gear as much as it can but is trying to force itself. like its not sending a signal to the car that hey ive turned as much as i can, very weird, i have a new motor on the way, it will be here friday, looking at the diagram it appears to be m2/20, i attached some pics and a link to a vid to show my process, the vid shows it makes out and the motor still trying to turn, the formes i have looked at all describe either broken linkage or motor just not working, not that it continues to just keep turning, thank you for your response
video link: https://drive.google.com/file/d/1OG6...ew?usp=sharing
MBWorld Fanatic!
Joined: Dec 2003
Posts: 3,275
Likes: 236
From: BC, Canada
2003 C230K Coupe Orion Blue
Are your linkages okay as well?
I find the that the teeth on the black gear tend to go first. Not the teeth seen in your photo but on the other side of the gear (the ones that mesh with the big white gear). In both of my failed motors the teeth I mentioned were worn down. I also had a tooth break off the big white gear, which killed the ability to control my windshield defrost dampers.
I see a lot of black stuff around the teeth of the big white gear. That would be bits of the black gear mentioned above.
The motors themselves provide feedback via resistance (ie the output can't rotate anymore) to know where the ends of travel are. When the gears fail then the motor gets confused and keeps driving the output, hence the clicking sound as the teeth skip or the output shaft pops while spinning inside a broken linkage.
I find the that the teeth on the black gear tend to go first. Not the teeth seen in your photo but on the other side of the gear (the ones that mesh with the big white gear). In both of my failed motors the teeth I mentioned were worn down. I also had a tooth break off the big white gear, which killed the ability to control my windshield defrost dampers.
I see a lot of black stuff around the teeth of the big white gear. That would be bits of the black gear mentioned above.
The motors themselves provide feedback via resistance (ie the output can't rotate anymore) to know where the ends of travel are. When the gears fail then the motor gets confused and keeps driving the output, hence the clicking sound as the teeth skip or the output shaft pops while spinning inside a broken linkage.
Last edited by slammer111; May 4, 2020 at 11:28 PM.
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w203 (c240)
that would make alot of sense actually, thank you for the response on how they operate, i was very i was wondering how they knew when to stop, upon closer look i see what you are talking about, what i though was grime or grease, is the wear shavings of the plastic from the motor being confused and continually skipping for force turning, i have another motor coming to me on friday, we will see ill update you , do you know where i can buy that big white wheel individually that attaches to the outside of the motor,
thank you again
btw love your car in the pic
, do you know where i can buy that big white wheel individually that attaches to the outside of the motor,thank you again
btw love your car in the pic
MBWorld Fanatic!
Joined: Dec 2003
Posts: 3,275
Likes: 236
From: BC, Canada
2003 C230K Coupe Orion Blue
Yes the black stuff is bits of the black gear. If you look at the rest of the big white gear (outside the normal of range of travel) you'll see that the original grease is actually cream yellow.
Sadly I don't know where to find any replacement gears for this thing. It's a real shame because most of the stepper motor internal problems are caused by broken gears and not the motor itself dying. Only the manufacturer (Behr) would know where to get these things. MB won't. To be honest it's almost not worth the trouble trying to source them.
When you receive the new stepper motor assembly, can you open up the gearbox and post some pictures? Specifically wondering if they updated the gear materials. Not sure about every gear but the black one in my old motor (Behr EAB501) is stamped PEEK CF-30, (polyether ether ketone, carbon fibre 30%). The big white gear is stamped PA66-GF50 (polyamide 6.6, 50% glass fibre). Super tiny writing. I assume the other 2 smaller white gears are the same material as I couldn't find any markings on them.
If you see any writing on the gears, can you please post them here, as well as the external markings on the new stepper motor? I'm guessing your new motor will be a Behr EAB502, which I assume supersedes the original EAB501 installed in most W203s for this era.
Thanks for the compliment.
Sadly I don't know where to find any replacement gears for this thing. It's a real shame because most of the stepper motor internal problems are caused by broken gears and not the motor itself dying. Only the manufacturer (Behr) would know where to get these things. MB won't. To be honest it's almost not worth the trouble trying to source them.
When you receive the new stepper motor assembly, can you open up the gearbox and post some pictures? Specifically wondering if they updated the gear materials. Not sure about every gear but the black one in my old motor (Behr EAB501) is stamped PEEK CF-30, (polyether ether ketone, carbon fibre 30%). The big white gear is stamped PA66-GF50 (polyamide 6.6, 50% glass fibre). Super tiny writing. I assume the other 2 smaller white gears are the same material as I couldn't find any markings on them.
If you see any writing on the gears, can you please post them here, as well as the external markings on the new stepper motor? I'm guessing your new motor will be a Behr EAB502, which I assume supersedes the original EAB501 installed in most W203s for this era.
Thanks for the compliment.
Last edited by slammer111; May 5, 2020 at 05:15 AM.
Thread Starter
Newbie
Joined: May 2020
Posts: 4
Likes: 0
w203 (c240)
Yes the black stuff is bits of the black gear. If you look at the rest of the big white gear (outside the normal of range of travel) you'll see that the original grease is actually cream yellow.
Sadly I don't know where to find any replacement gears for this thing. It's a real shame because most of the stepper motor internal problems are caused by broken gears and not the motor itself dying. Only the manufacturer (Behr) would know where to get these things. MB won't. To be honest it's almost not worth the trouble trying to source them.
When you receive the new stepper motor assembly, can you open up the gearbox and post some pictures? Specifically wondering if they updated the gear materials. Not sure about every gear but the black one in my old motor (Behr EAB501) is stamped PEEK CF-30, (polyether ether ketone, carbon fibre 30%). The big white gear is stamped PA66-GF50 (polyamide 6.6, 50% glass fibre). Super tiny writing. I assume the other 2 smaller white gears are the same material as I couldn't find any markings on them.
If you see any writing on the gears, can you please post them here, as well as the external markings on the new stepper motor? I'm guessing your new motor will be a Behr EAB502, which I assume supersedes the original EAB501 installed in most W203s for this era.
Thanks for the compliment.
Sadly I don't know where to find any replacement gears for this thing. It's a real shame because most of the stepper motor internal problems are caused by broken gears and not the motor itself dying. Only the manufacturer (Behr) would know where to get these things. MB won't. To be honest it's almost not worth the trouble trying to source them.
When you receive the new stepper motor assembly, can you open up the gearbox and post some pictures? Specifically wondering if they updated the gear materials. Not sure about every gear but the black one in my old motor (Behr EAB501) is stamped PEEK CF-30, (polyether ether ketone, carbon fibre 30%). The big white gear is stamped PA66-GF50 (polyamide 6.6, 50% glass fibre). Super tiny writing. I assume the other 2 smaller white gears are the same material as I couldn't find any markings on them.
If you see any writing on the gears, can you please post them here, as well as the external markings on the new stepper motor? I'm guessing your new motor will be a Behr EAB502, which I assume supersedes the original EAB501 installed in most W203s for this era.
Thanks for the compliment.
got the new motor in
that was the issue, replaced and line up the teeth as good as a can, and plug her in and now adjust perfectly (well about 98 percent ) but not bad for 16 bucks
the part actually came from a w211 (2003 e320) but the motors are the same, next ill be doing my compressor
any recomdations for what ill need? should i do the condenser as well?
what happend to the old compressor was it seized and took the belt and pully with it, ive been running a shorter serp belt to bypass it,
also might try tinting myself, but we will see,
i attached a pic of the new motor
