Noisy Air Conditioner ?? Stepper Motor Replacement / Clicking & Hissing
#601
Junior Member
The stepper motors are used. Still a bad idea?
#602
MBWorld Fanatic!
You lost me. Replace the motors? No. Replace the arms? Yes but only with new ones.
#603
Junior Member
#604
MBWorld Fanatic!
I wouldn't. You know your motors are good .... at least up until now. You wouldn't know anything about the replacements. My experience is the motors are pretty solid. There's not much to them to go wrong other than the clutch and if they don't 'pop' then they aren't slipping. If you're worried about them buy new ones.
#605
Junior Member
I wouldn't. You know your motors are good .... at least up until now. You wouldn't know anything about the replacements. My experience is the motors are pretty solid. There's not much to them to go wrong other than the clutch and if they don't 'pop' then they aren't slipping. If you're worried about them buy new ones.
#606
Hi everyone,
I am somewhat new to MB, currently owning a 2001 c220 cdi, and I am experiencing HVAC unit issues. It all started with a periodical ticking noise under the central console ( sounded like it was something under the cd player). Also after the noises appeared, with the air conditioning on, the left side blows cold like it supposed to, on the right, the upper side blows somewhat hot air, but at the feet, extra hot air. Today after ordering the two linkages, and the repair kit (all of the plastic sprockets), i took the courage and dismantled the dashboard. The car is equipped with the 6 flap actuator, what i found is that the ticking noise was coming from motor M2/21, the sprocket with the hex that goes on the motor is cracked. I thought that this will fix things, i changed the linkage, the 3 plastic sprockets, checked if the flap is not stuck, and made a test run, what happens is that the actuator does not stop from rotating, the gears ( upper one that is connected by the teeth) disengage, making noises just like before... I tried to fit them, as far as i know, the one that is connected to the upper flap has a notch on it, the hex one has a small cut, these need to be aligned. Also, if i connect the actuator to the system while it's not attached to any kind of linkages, it will spin without stopping, continuously. What could be wrong ?
I am somewhat new to MB, currently owning a 2001 c220 cdi, and I am experiencing HVAC unit issues. It all started with a periodical ticking noise under the central console ( sounded like it was something under the cd player). Also after the noises appeared, with the air conditioning on, the left side blows cold like it supposed to, on the right, the upper side blows somewhat hot air, but at the feet, extra hot air. Today after ordering the two linkages, and the repair kit (all of the plastic sprockets), i took the courage and dismantled the dashboard. The car is equipped with the 6 flap actuator, what i found is that the ticking noise was coming from motor M2/21, the sprocket with the hex that goes on the motor is cracked. I thought that this will fix things, i changed the linkage, the 3 plastic sprockets, checked if the flap is not stuck, and made a test run, what happens is that the actuator does not stop from rotating, the gears ( upper one that is connected by the teeth) disengage, making noises just like before... I tried to fit them, as far as i know, the one that is connected to the upper flap has a notch on it, the hex one has a small cut, these need to be aligned. Also, if i connect the actuator to the system while it's not attached to any kind of linkages, it will spin without stopping, continuously. What could be wrong ?
Last edited by n.emil; 05-07-2018 at 03:29 PM.
#607
MBWorld Fanatic!
That's what happens when they're not connected to the linkage. They need resistance/to stop to calibrate their position.
#608
Member
I am stuck trying to replace the defrost flap motor on a 2003 C230 sedan. Managed to remove the lower dash, dropped the wheel, side vents and screws holding the upper dash in place. I did leave the center console plastic cage in place, since I did not think it would be necessary to access the defrost motor. But I cannot remove the windshield cowl no matter what. Tried to place wedges underneath to loosen it, but it feels like it is glued to the windshield no matter how hard I pull. The upper dash feels loose all around including the windshield side except for where the side pillars are. Any ideas? Thanks!
#609
MBWorld Fanatic!
#610
Member
So I finally was able to pop off the water collector from the windshield. The trick was using a hook and pulling up from the LOWER lip, starting on the passenger side.
Last edited by wanderlust360; 05-13-2018 at 07:58 PM.
#611
First, thanks to all the folks who have taken a moment to post pics, diagrams, failures and successes. Really been helpful to me. I am stationed in Spain.....and recently bought a European spec 2001 C220 CDI classic that a local mechanic checked and said was in good condition. 130k miles. The car looked good....and though I am not a mechanic I have worked on cars to a degree out of necessity....so the basics also looked good to me.
As I discovered within a month, the car had an intermittent heating issue (warm air not hot), and strange clicking noises from the center of the dash. I took the car to the mechanic who said everything was good....and he kept the car for a month and replaced the secondary water pump that sits just outside the coolant tank, repaired some of the internal parts of a couple of actuators, and recharged the AC system. I got the car back because I was getting mad that it was taking so long to make these repairs, and as I had just moved into a home with a 2 car garage and I had tools....I figured I could complete these repairs.
So my experiences with MB truly began. I really wish I would have read some of these forums prior to purchasing the car....it would have impacted my decision and provided me with some things to check more thoroughly. While there is a lot about the car I enjoy, this issue is truly a pain in the rear.
Using various articles from here, U-tube, and Pelican parts.....I now have stripped down the MB and the dashboard is out. I have the digital dual zone control....and have replaced that with a used one.....the original one would cause problems like turning on without me touching it, and not in auto mode. I have also found 2 actuators bad with internal plastic gear teeth stripped (yes, I took them apart) M2/20 and M2/5. M2/5 was the source of the constant clicking sound that became progressively worse, and would not stop until turning off the car. I also found bad plastic gears on 2/19 and 2/11.
I have replaced the actuators with used ones from EBAY....I bought 3 for $54 from the States.....you can turn the actuators but not by hand, if you put on the plastic gear you can make the actuator work....and spin it 360 degrees to see if you hit points of resistance. On the two bad ones I have, that is what happens. Very noticeable. As someone suggested....you could try to open the actuators and merely reposition the bad area of the gear to a spot that will not be used.....but as this evolution of merely getting to a actuator is so painful I am just replacing them so hopefully I will not have to deal with this issue again.
I have the plastic long lever for M2/11 on order from Pelican Parts, as well as the other plastic gear bag that they sell. Hopefully it will arrive soon.
I do have the car apart....so if anyone wants some pics of specific areas please advise and I can take and post. Trust me I have several already.
But NONE of the above was the cause of my loss of heat. After paying attention to the temp, noted that it was way below the 80c mark. As I wanted to change the oil and filter anyhow, I also ordered and changed the thermostat....which on MB comes as a whole unit. This was it's own pain in the *** to relace....but when I pulled out the original thermostat I discovered that the "guts" were missing....i.e. the actual thermostat had been removed. After making the change...and forgetting to connect the bottom tube out of the thermostat which then required me to take the whole thing apart again......grrrrr....the car now gets up to 80c, and I have hot air blowing.
I currently have all the actuators hooked up except for M2/11, and when I run the HVAC test everything seems to shift smooth with one exception.
Which leads to my questions at this point. M2/6 is making a small click at the end of one of it's evolutions during the HVAC test. Looking at it, one of the large plastic gears seems to flex slightly out of position, like it is binding, but then pops right back into place. So M2/6 is a blend air actuator....but I am concerned due to it's location and the amount of plastic gears I see hanging on it. I don't want to take it off and be faced with not being able to get it back on without completely removing the HVAC system. Has anyone removed this actuator before, and by chance have some clear pictures of the gears and such? Any advice?
Another question....that I think I have read the answer to here....but at the top of the HVAC....when I turn up the heat to MAX.....I get heat from the front two square vents that would go to the center vents on the dashboard.....but the rear vent, guessing defrost.....remains cold almost like AC. And no, the defrost is not selected, and I am in manual control of temp and actuator position at this time. This just doesn't seem right, but think I have read that MB does this to keep windows clear? Just seems like if you want heat in the cabin, would kind of defeat the purpose to also have cold air blowing via the defrost.
That is all for now.....but I have also replaced the center LCD in the instrument panel that would fade out in sunlight after the car was sitting during the day.....I have replaced the passenger side electric seat switch but still have a problem over there with a 30 amp fuse blowing. I have ordered the light sensor as the automatic lights were intermittent, and have ordered another overhead center light console as the original one had been modified, and the center light did not work correctly as there was always 12 vdc present at the light, which would remain on at all times.
Thanks for any assistance with this!!
As I discovered within a month, the car had an intermittent heating issue (warm air not hot), and strange clicking noises from the center of the dash. I took the car to the mechanic who said everything was good....and he kept the car for a month and replaced the secondary water pump that sits just outside the coolant tank, repaired some of the internal parts of a couple of actuators, and recharged the AC system. I got the car back because I was getting mad that it was taking so long to make these repairs, and as I had just moved into a home with a 2 car garage and I had tools....I figured I could complete these repairs.
So my experiences with MB truly began. I really wish I would have read some of these forums prior to purchasing the car....it would have impacted my decision and provided me with some things to check more thoroughly. While there is a lot about the car I enjoy, this issue is truly a pain in the rear.
Using various articles from here, U-tube, and Pelican parts.....I now have stripped down the MB and the dashboard is out. I have the digital dual zone control....and have replaced that with a used one.....the original one would cause problems like turning on without me touching it, and not in auto mode. I have also found 2 actuators bad with internal plastic gear teeth stripped (yes, I took them apart) M2/20 and M2/5. M2/5 was the source of the constant clicking sound that became progressively worse, and would not stop until turning off the car. I also found bad plastic gears on 2/19 and 2/11.
I have replaced the actuators with used ones from EBAY....I bought 3 for $54 from the States.....you can turn the actuators but not by hand, if you put on the plastic gear you can make the actuator work....and spin it 360 degrees to see if you hit points of resistance. On the two bad ones I have, that is what happens. Very noticeable. As someone suggested....you could try to open the actuators and merely reposition the bad area of the gear to a spot that will not be used.....but as this evolution of merely getting to a actuator is so painful I am just replacing them so hopefully I will not have to deal with this issue again.
I have the plastic long lever for M2/11 on order from Pelican Parts, as well as the other plastic gear bag that they sell. Hopefully it will arrive soon.
I do have the car apart....so if anyone wants some pics of specific areas please advise and I can take and post. Trust me I have several already.
But NONE of the above was the cause of my loss of heat. After paying attention to the temp, noted that it was way below the 80c mark. As I wanted to change the oil and filter anyhow, I also ordered and changed the thermostat....which on MB comes as a whole unit. This was it's own pain in the *** to relace....but when I pulled out the original thermostat I discovered that the "guts" were missing....i.e. the actual thermostat had been removed. After making the change...and forgetting to connect the bottom tube out of the thermostat which then required me to take the whole thing apart again......grrrrr....the car now gets up to 80c, and I have hot air blowing.
I currently have all the actuators hooked up except for M2/11, and when I run the HVAC test everything seems to shift smooth with one exception.
Which leads to my questions at this point. M2/6 is making a small click at the end of one of it's evolutions during the HVAC test. Looking at it, one of the large plastic gears seems to flex slightly out of position, like it is binding, but then pops right back into place. So M2/6 is a blend air actuator....but I am concerned due to it's location and the amount of plastic gears I see hanging on it. I don't want to take it off and be faced with not being able to get it back on without completely removing the HVAC system. Has anyone removed this actuator before, and by chance have some clear pictures of the gears and such? Any advice?
Another question....that I think I have read the answer to here....but at the top of the HVAC....when I turn up the heat to MAX.....I get heat from the front two square vents that would go to the center vents on the dashboard.....but the rear vent, guessing defrost.....remains cold almost like AC. And no, the defrost is not selected, and I am in manual control of temp and actuator position at this time. This just doesn't seem right, but think I have read that MB does this to keep windows clear? Just seems like if you want heat in the cabin, would kind of defeat the purpose to also have cold air blowing via the defrost.
That is all for now.....but I have also replaced the center LCD in the instrument panel that would fade out in sunlight after the car was sitting during the day.....I have replaced the passenger side electric seat switch but still have a problem over there with a 30 amp fuse blowing. I have ordered the light sensor as the automatic lights were intermittent, and have ordered another overhead center light console as the original one had been modified, and the center light did not work correctly as there was always 12 vdc present at the light, which would remain on at all times.
Thanks for any assistance with this!!
#612
I am stuck trying to replace the defrost flap motor on a 2003 C230 sedan. Managed to remove the lower dash, dropped the wheel, side vents and screws holding the upper dash in place. I did leave the center console plastic cage in place, since I did not think it would be necessary to access the defrost motor. But I cannot remove the windshield cowl no matter what. Tried to place wedges underneath to loosen it, but it feels like it is glued to the windshield no matter how hard I pull. The upper dash feels loose all around including the windshield side except for where the side pillars are. Any ideas? Thanks!
#613
Oh, one more question that I forgot. I have noticed a long plastic/metal connector piece on some pics going I think from M2/10 - M2/11. While this piece is included in one of the parts kits I ordered from Pelican....is it supposed to be there for my car??? If so, it is not installed. What is it for?
#614
Clicking on startup, no air to feet
Just the other day the airflow to the feet was working and now nada. Clicking has been happening under dash for only a couple weeks. A.c. works to all other vents.
anyone in the Tucson area that can help me follow these instructions? 27 yr old female, first Mercedes, just changer brake pads for the first time last week so could use some help/supervision with this.
anyone in the Tucson area that can help me follow these instructions? 27 yr old female, first Mercedes, just changer brake pads for the first time last week so could use some help/supervision with this.
#615
Well Sweet Hart that certainly sounds like one of those plastic footwell pieces has cracked or broken. As I mentioned....my count is 2 actuators with worn internal gear teeth, and 2 plastic gears external to the actuator motor. One was to the footwell.
I am not an expert here....but think to get to the area of concern, you are going to have to do same thing I did.....remove pretty much entire front including dashboard. I did not drop my steering wheel, nor did I have to take off all of my arm rest area. Someone had already been working in my used car, so some of the screws were missing or not tight.....especially in the center console/radio/heater control area.
There are instructions on this site as to how to take apart your benz. Be patient, take pics and you should be fine. Took me half a day to just get things apart to the point where I could troubleshoot. And it helps to be able to contort your body up under the glove box and steering wheel, though my back hurt the next day. I have a set of Torx wrenches that look like an Allen set, but Torx at the ends. Between those and a screwdriver set with Torx on the ends (think T15 is the magic number for the majority of the screws encountered) I was able to disassembly things. Now I am just awaiting more parts from Pelican.
Good luck....
I am not an expert here....but think to get to the area of concern, you are going to have to do same thing I did.....remove pretty much entire front including dashboard. I did not drop my steering wheel, nor did I have to take off all of my arm rest area. Someone had already been working in my used car, so some of the screws were missing or not tight.....especially in the center console/radio/heater control area.
There are instructions on this site as to how to take apart your benz. Be patient, take pics and you should be fine. Took me half a day to just get things apart to the point where I could troubleshoot. And it helps to be able to contort your body up under the glove box and steering wheel, though my back hurt the next day. I have a set of Torx wrenches that look like an Allen set, but Torx at the ends. Between those and a screwdriver set with Torx on the ends (think T15 is the magic number for the majority of the screws encountered) I was able to disassembly things. Now I am just awaiting more parts from Pelican.
Good luck....
Last edited by Trongod; 05-20-2018 at 07:56 AM.
#616
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Join Date: Dec 2003
Location: Vancouver, BC, Canada
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2003 C230K Coupe Orion Blue
The upper dash needs to be removed to get to this thing.
#617
Member
Ended-up replacing the clicking defrost motor (M2/16) and uncovered a host of other issues: broken footwell actuator arm and cracked left blend (or fresh) air actuator gear. Replaced everything, synchronized the flaps, and put the dashboard back together. Make sure to reconnect ALL electrical cables before turning on the ignition, or you will end-up with an SRS fault code. The whole ordeal took me almost an entire week
All the vents seem to function properly, but the a/c is acting a little odd on full automatic mode. It continuously tries to adjust the temperature by randomly opening/closing vents. Sometimes I also do get cold air followed by heated air in some vents. The only thing that seems to help temporarily is turning the temperature knobs all the way to the right/left, then back to desired temperature. Could it be a failing control module, or some other a/c sensor somewhere?
Thank-you for all the guidance so far!
Location of broken motor/linkages
All the vents seem to function properly, but the a/c is acting a little odd on full automatic mode. It continuously tries to adjust the temperature by randomly opening/closing vents. Sometimes I also do get cold air followed by heated air in some vents. The only thing that seems to help temporarily is turning the temperature knobs all the way to the right/left, then back to desired temperature. Could it be a failing control module, or some other a/c sensor somewhere?
Thank-you for all the guidance so far!
Location of broken motor/linkages
Last edited by wanderlust360; 05-24-2018 at 02:34 PM.
#618
Ended-up replacing the clicking defrost motor (M2/16) and uncovered a host of other issues: broken footwell actuator arm and cracked left blend (or fresh) air actuator gear. Replaced everything, synchronized the flaps, and put the dashboard back together. Make sure to reconnect ALL electrical cables before turning on the ignition, or you will end-up with an SRS fault code. The whole ordeal took me almost an entire week
All the vents seem to function properly, but the a/c is acting a little odd on full automatic mode. It continuously tries to adjust the temperature by randomly opening/closing vents. Sometimes I also do get cold air followed by heated air in some vents. The only thing that seems to help temporarily is turning the temperature knobs all the way to the right/left, then back to desired temperature. Could it be a failing control module, or some other a/c sensor somewhere?
Thank-you for all the guidance so far!
Location of broken motor/linkages
All the vents seem to function properly, but the a/c is acting a little odd on full automatic mode. It continuously tries to adjust the temperature by randomly opening/closing vents. Sometimes I also do get cold air followed by heated air in some vents. The only thing that seems to help temporarily is turning the temperature knobs all the way to the right/left, then back to desired temperature. Could it be a failing control module, or some other a/c sensor somewhere?
Thank-you for all the guidance so far!
Location of broken motor/linkages
I ordered replacement plastic arms and gears and pretty much replaced everything I could, even if it was not broken.....as I do not want to have to do this exercise again while I own this car.
Let me ask you a couple of questions....you mention the SRS fault......did you disconnect your front passenger side air bag when you removed your dash, or did you leave it in?
Also....the left blend air actuator gear that you said had a crack.....which gear was that on? Internal to the actuator or on one of those external plastic gears? Reason I ask.....when the climate control runs on my car, and the left side blend actuator cycles from one end stop to the other, I do see where it appears to hit a slight snag at one end....but when I removed the actuator and looked....I could not find anything cracked and it seemed to cycle ok manually when I moved the gears by hand.
#619
Member
Glad your clicking noises are gone! Must be a slightly different stepper motor configuration. I do have the dual climate control, but with the manual knobs and not digital. Regarding the SRS fault. I did not disconnect any of the airbags. I did unbolt the passenger airbag, and left it connected but upside down on the dash. I assumed leaving the light switch unplugged triggered the SRS fault, unless the system can detect if an airbag is not positioned properly. I had to have the code cleared by a shop since it was permanent. The cracked gear was the external gear to the right (sandwiched between the yellow link and the other white gear).
#620
Glad your clicking noises are gone! Must be a slightly different stepper motor configuration. I do have the dual climate control, but with the manual knobs and not digital. Regarding the SRS fault. I did not disconnect any of the airbags. I did unbolt the passenger airbag, and left it connected but upside down on the dash. I assumed leaving the light switch unplugged triggered the SRS fault, unless the system can detect if an airbag is not positioned properly. I had to have the code cleared by a shop since it was permanent. The cracked gear was the external gear to the right (sandwiched between the yellow link and the other white gear).
WRT the SRS bag....well I disconnected mine and have powered it up since then.....I read afterwards that this was probably a bad idea and would lead to the SRS fault which apparently may not clear out once everything is back together. I guess I am going to have to go ahead and order one of those code readers.....sigh. I did read a report where someone had the same issue, and the fault went away after 30-40 starts.....maybe I will get lucky like that.....
#621
No air to feet
Hi guys. I went through the whole thread but it’s pretty long and I didn’t really see anything other than a post above mine. But I’m not getting any air hot or cold to the feet on either side. I can hear the air being switched bc once I turn the knob to the feet the blowing gets loud like it’s being restricted (since it obviously is) is this a sign of the stepper motor issue? Also is there a way to resync the diverters? I was reading on the older dashes you could hold recirc button and defrost but I have the newer dash with all the analog buttons next to the radio. It’s an 07 C230. And like I said air blows out from everywhere but the feet.
#622
Senior Member
I’be seen in other threads about getting codes out of the HVAC unit.
Is there a way on 2005 C230 Coupe with dual climate control to do self diagnosis to find out what is actually wrong with the system?
When I put mine in self diagnosis now the flashing lights so not stop, so there is something wrong with it.
Is there a way on 2005 C230 Coupe with dual climate control to do self diagnosis to find out what is actually wrong with the system?
When I put mine in self diagnosis now the flashing lights so not stop, so there is something wrong with it.
#623
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Join Date: Jan 2016
Location: Auckland NZ
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1987 W124 300E
Hi, you're right, getting all that upper dash apart is a real pain, then there's the frame, so much work.
I read up all I could and decided there may be a quicker way. I was trying to get at the stepper that was clicking, the one most forward
under the w/screen. Normally the entire dash has to be freed up to get it out. I didn't want to take out the rest of the w/wiper assy to get at the bolt and big washer hiding down there under the hoses behind the engine.
Under the hood and the w/screen there is a sloping piece of firewall next to the cabin-filter housing. With that out of the way you can actually
feel the stepper in question. So, I used a 2.5 inch drill, the ones you use to cut holes in sheet metal. They come with a drill-bit which gets you started in the
steel and I started the drill at a 90 angle to the firewall and broke through the firewall. I then gently moved the drill into a vertical position and the top of the drill piece was now cutting the firewall at its topmost edge and the drill bit was keeping everything lined up.. Slowly but surely the drill cut down and around until the last little bit could be removed by hand. How long? About seven minutes. I cleaned the edge up with a round file and it looked fine; it can be covered with a piece of sound-proofing pad so it looks original and its there in case it ever needs to be done a second time. Then one can remove the cable and two of the three screws, the first or last one can be reached from inside the car; the stepper comes out of that hole. I will admit to slacking the bolts holding the frame and pressing down inside the car giving enough room to get at the three screws.
I read up all I could and decided there may be a quicker way. I was trying to get at the stepper that was clicking, the one most forward
under the w/screen. Normally the entire dash has to be freed up to get it out. I didn't want to take out the rest of the w/wiper assy to get at the bolt and big washer hiding down there under the hoses behind the engine.
Under the hood and the w/screen there is a sloping piece of firewall next to the cabin-filter housing. With that out of the way you can actually
feel the stepper in question. So, I used a 2.5 inch drill, the ones you use to cut holes in sheet metal. They come with a drill-bit which gets you started in the
steel and I started the drill at a 90 angle to the firewall and broke through the firewall. I then gently moved the drill into a vertical position and the top of the drill piece was now cutting the firewall at its topmost edge and the drill bit was keeping everything lined up.. Slowly but surely the drill cut down and around until the last little bit could be removed by hand. How long? About seven minutes. I cleaned the edge up with a round file and it looked fine; it can be covered with a piece of sound-proofing pad so it looks original and its there in case it ever needs to be done a second time. Then one can remove the cable and two of the three screws, the first or last one can be reached from inside the car; the stepper comes out of that hole. I will admit to slacking the bolts holding the frame and pressing down inside the car giving enough room to get at the three screws.
#624
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Location: Auckland NZ
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1987 W124 300E
HI. I've my own experience with the dreaded clicking on 2001 C240. My faulty stepper was the Charcoal filter a32m2.
I removed the stepper (my method) and saw the two plastic gears. They were different colours so I suspected the job's been done before, something I guessed
whilst I was digging my way in there. So, the two gears were damaged over a space of about six teeth each.
I had read al the stories so I knew what the problem was going be. I ordered a second-hand one before I started to dismantle the dash but now I saw I needed gears as well. You know, I've read so many heart breaking tales of this problem with the W203 C-class but I've never heard anyone say why it happens. When the gears arrived
I put the 'driven' gear in place in the housing so I could work out the initial setting. It moved fine in the housing, it wasn't being impeded. This particular gear has a leg which sticks out and comes up against an abutment in the housing to create a full stop open and full stop closed situation. It's was interesting to note that the gear has less than 90 degrees from full open to full shut. I put the wiring connection back onto the stepper, switched on the ignition to see the driving spindle start to rotate in an anti-clockwise direction. It went on until it covered around 380 degrees when it stopped. If the gear driven can only manage less than 90 why do we need 380?
Like a lot of other folk I decided it must have a clutch of some description. So, I switched it off and on again and it started to rotate but this time I put a socket on the driving shaft and then a small ratchet and offered resistance by way of the ratchet. They are very powerful. I kept a good amount of pressure on it and it again did it's
380 degrees! Now I tried the stepper I had bought and it did exactly the same. So, as I knew I wasn't going to use my stepper I dismantled it. I didn't realise they had
2 set's of windings and they don't have a clutch, just putting this together would destroy the gears the first time they were used. What if the two sets of windings allow it to reverse the current once a certain pressure is reached and that allows it to travel back to the other stop of the driven gear where it would disconnect the current
again. I'm not sure what or where the current would be switched, if that is they way it's supposed to work. Unfortunately, I think I broke one wire for one of the winding sets when I dismantled my stepper or is that broken wire not my doing? Maybe that's the reason the gears were destroyed in the first place. I'll dismantle the remaining
stepper to see if it has a broken wire also. I tried to find a drawing showing there construction but I've found anything yet.
I removed the stepper (my method) and saw the two plastic gears. They were different colours so I suspected the job's been done before, something I guessed
whilst I was digging my way in there. So, the two gears were damaged over a space of about six teeth each.
I had read al the stories so I knew what the problem was going be. I ordered a second-hand one before I started to dismantle the dash but now I saw I needed gears as well. You know, I've read so many heart breaking tales of this problem with the W203 C-class but I've never heard anyone say why it happens. When the gears arrived
I put the 'driven' gear in place in the housing so I could work out the initial setting. It moved fine in the housing, it wasn't being impeded. This particular gear has a leg which sticks out and comes up against an abutment in the housing to create a full stop open and full stop closed situation. It's was interesting to note that the gear has less than 90 degrees from full open to full shut. I put the wiring connection back onto the stepper, switched on the ignition to see the driving spindle start to rotate in an anti-clockwise direction. It went on until it covered around 380 degrees when it stopped. If the gear driven can only manage less than 90 why do we need 380?
Like a lot of other folk I decided it must have a clutch of some description. So, I switched it off and on again and it started to rotate but this time I put a socket on the driving shaft and then a small ratchet and offered resistance by way of the ratchet. They are very powerful. I kept a good amount of pressure on it and it again did it's
380 degrees! Now I tried the stepper I had bought and it did exactly the same. So, as I knew I wasn't going to use my stepper I dismantled it. I didn't realise they had
2 set's of windings and they don't have a clutch, just putting this together would destroy the gears the first time they were used. What if the two sets of windings allow it to reverse the current once a certain pressure is reached and that allows it to travel back to the other stop of the driven gear where it would disconnect the current
again. I'm not sure what or where the current would be switched, if that is they way it's supposed to work. Unfortunately, I think I broke one wire for one of the winding sets when I dismantled my stepper or is that broken wire not my doing? Maybe that's the reason the gears were destroyed in the first place. I'll dismantle the remaining
stepper to see if it has a broken wire also. I tried to find a drawing showing there construction but I've found anything yet.