Heater control knob stiff
- Thread starter dpw
- Start date
jmoller99
Own a DAD ODB2 Unit.
In this stream of replies is my solution to this same problem. My cables were flexing (the Sprinter cables are stranded wire) and I needed to add a spring to help compensate for the flex - it was added behind the cable mechanisum. I reposted the pictures of the fix here. The spring came from a local hardware store (Lowes).
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Andyandyandy
2005 Cargo 2500
Jmoller, I might try that wth the spring; it could help. However, my control is still stuck even with the cables totally removed. I'm thinking it could be jambed somewhere inside the black box. I might open this thing up if no one stops me in time.
Andy
Andy
seans
Member
I opened my control box to repair the temperature control. I thought my hand was on the air direction control which normally requires a good amount of force to rotate. When I applied that to the temperature control I broke the potentiometer inside.
While disassembling the control, there were some small plastic tabs that hold some of the parts together. A few of these snapped on me when I opened the box.
I think if you are very careful, and perform this in a very warm room with the box preheated, the plastic may be less brittle and you may be able to keep the tabs from breaking. If done when it is cold, the plastic tabs may break before they yield sufficiently.
I had no problem assembling the box as the assembly of other parts held in the parts with the broken tabs. However, my recirculation light does not come on and recirculation doesn't work, and sometimes the front AC does not come on. I have not diagnosed these, and think it may be a loose connector.
Given that the alternative is to replace your box (possibly from a salvaged Sprinter) I would carefully try to fix it myself. Even though I have new issues, they are minor compared to my Sprinter's prior state of having no cabin heat. However, if your knob turns fine when the control cable is not connected, you might try simulating the forces the cable would apply, and if doing that does not cause binding, opening the box may not be fruitful.
While disassembling the control, there were some small plastic tabs that hold some of the parts together. A few of these snapped on me when I opened the box.
I think if you are very careful, and perform this in a very warm room with the box preheated, the plastic may be less brittle and you may be able to keep the tabs from breaking. If done when it is cold, the plastic tabs may break before they yield sufficiently.
I had no problem assembling the box as the assembly of other parts held in the parts with the broken tabs. However, my recirculation light does not come on and recirculation doesn't work, and sometimes the front AC does not come on. I have not diagnosed these, and think it may be a loose connector.
Given that the alternative is to replace your box (possibly from a salvaged Sprinter) I would carefully try to fix it myself. Even though I have new issues, they are minor compared to my Sprinter's prior state of having no cabin heat. However, if your knob turns fine when the control cable is not connected, you might try simulating the forces the cable would apply, and if doing that does not cause binding, opening the box may not be fruitful.
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Andyandyandy
2005 Cargo 2500
I have opened up the box and found the problem. A piece of the plastic that forms the path in the cam had broken away, allowing the follower to fall into a void where it got stuck. Due to the shape of the chip, turning counterclockwise allowed the follower to briefly stay on track, where turning clockwise past the chip shunted it out of the track. I am almost finished putting it back together, and will report back later, hopefully with some photos.
Andy
Andy
Andyandyandy
2005 Cargo 2500
Well, too late for the light bulbs, but the good news is that everything is back together and working.
I ended up sawing open the back of the housing with a little modelmaker's backsaw in order to extract the cam. It's something like cutting the top out of a pumpkin, in that you want to make sure that it locates itself back together and doesn't slide around. A Dremel with the small circular saw might work too, but the handsaw is probably better. ABS gets pretty gummy when you cut it.
I have some photos, but I can't for the life of me figure out how to resize them to put them on here.
Anyways, I took out the cam, chiseled away the broken section, and cut a piece of acrylic to match the proper shape of the track. I roughed up the nylon and used epoxy, but nylon doesn't glue very well, so I added a couple of brass tubular rivets to be sure. To finish up I just epoxied the housing back together and everything seems fine. Sorry it really would be better with the photos.
Andy
I ended up sawing open the back of the housing with a little modelmaker's backsaw in order to extract the cam. It's something like cutting the top out of a pumpkin, in that you want to make sure that it locates itself back together and doesn't slide around. A Dremel with the small circular saw might work too, but the handsaw is probably better. ABS gets pretty gummy when you cut it.
I have some photos, but I can't for the life of me figure out how to resize them to put them on here.
Anyways, I took out the cam, chiseled away the broken section, and cut a piece of acrylic to match the proper shape of the track. I roughed up the nylon and used epoxy, but nylon doesn't glue very well, so I added a couple of brass tubular rivets to be sure. To finish up I just epoxied the housing back together and everything seems fine. Sorry it really would be better with the photos.
Andy
Andyandyandy
2005 Cargo 2500
Well, this took me a long time, but here are a few photos that might be useful. The first shows the cam repaired with acrylic (a scrap of Corian countertop) and brass rivets. The brown is Sharpie ink that I scribed my line in. I left it on to show the shape better. The second and third photos show the back being cut off the module. I can't believe they couldn't spare the fifty cents it would have cost to make that part removeable. Anyways, in total I spent less than a dollar and maybe four hours from taking the dash apart to having it all working again. My feet are much warmer now.
Hope you're all enjoying the holidays.
Andy
Hope you're all enjoying the holidays.
Andy
Attachments
I want to thank all the posters who posted info on removing the cover, identifying screw locations, and suggesting being careful removing the cables. There is ZERO chance I would have attempted to repair this chronic problem with my van. (2006 2500, high roof, 140" wheelbase, 163,000 miles).
This is the 4th time the heat control system failed on this particular van. One time the dealer replaced the cable. Cost me $135 which I thought quite reasonable. (Happened a week after warranty expired, I kid you not). The next two times I was told the heater control failed and it was in the $800 range. The heat direction knob failed again last week. I went to I State in Minnesota and I was told the "fix" would be in the $2200 range, and would require replacing filters and other things. Parts would have to be shipped in. (This was part of a larger $6000+ quote for other repairs.) I felt they were looking at the wrong thing or were trying to scam me. So I declined that work. After reading the posts on this thread I decided to try it and just completed the repair myself. The white cable had bent (failed) behind the heat control module. The replacement cable cost $6 at a dealer. I sprayed a bunch (I hope) of lithium grease between the sheath and the plastic covering adhering to the cable itself. It moved freely, but it moved freely before I applied the grease.
FYI: The "failed" white cable moved quite stiffly through the sheath after I straightened the bend.
I almost installed the spring that JMoller99 so cleverly installed. I think it's a great idea and will likely prevent problems in the future. However, I decided to wait and see what happens. It's not that big a deal getting into the unit so I'll take the chance.
Simultaneously the RSN so well documented on other threads reared it's ugly head. (the fix was part of the $6000 quote. (I ended up having them do $3200 worth of work.) Complete brake job, replace blower motor, Do something with the transmission, then reset adaptation. It actually made the RSN far WORSE!!
So now I'm going to do Dr A's fix next Thursday. (I offered to purchase a kit from the Good Dr but he must be taking a well deserved vacation. I can't wait till the van is back to being in good operating condition.
This is the 4th time the heat control system failed on this particular van. One time the dealer replaced the cable. Cost me $135 which I thought quite reasonable. (Happened a week after warranty expired, I kid you not). The next two times I was told the heater control failed and it was in the $800 range. The heat direction knob failed again last week. I went to I State in Minnesota and I was told the "fix" would be in the $2200 range, and would require replacing filters and other things. Parts would have to be shipped in. (This was part of a larger $6000+ quote for other repairs.) I felt they were looking at the wrong thing or were trying to scam me. So I declined that work. After reading the posts on this thread I decided to try it and just completed the repair myself. The white cable had bent (failed) behind the heat control module. The replacement cable cost $6 at a dealer. I sprayed a bunch (I hope) of lithium grease between the sheath and the plastic covering adhering to the cable itself. It moved freely, but it moved freely before I applied the grease.
FYI: The "failed" white cable moved quite stiffly through the sheath after I straightened the bend.
I almost installed the spring that JMoller99 so cleverly installed. I think it's a great idea and will likely prevent problems in the future. However, I decided to wait and see what happens. It's not that big a deal getting into the unit so I'll take the chance.
Simultaneously the RSN so well documented on other threads reared it's ugly head. (the fix was part of the $6000 quote. (I ended up having them do $3200 worth of work.) Complete brake job, replace blower motor, Do something with the transmission, then reset adaptation. It actually made the RSN far WORSE!!
So now I'm going to do Dr A's fix next Thursday. (I offered to purchase a kit from the Good Dr but he must be taking a well deserved vacation. I can't wait till the van is back to being in good operating condition.
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Lojack72
'02 DIY adventure van, 300K miles (210K by me)
To echo imshaken's comments, pulled mine apart last week. Couldn't change the vent knob, and also broke the temperature control blindly turning it too hard while thinking it was the former. Generous application of 5-minute epoxy and my temperature knob is holding, and hard to believe I can completely rotate the vent knob after a few shots of cable lube. Only wish I had taken jmoller99's advice, as now one of the lights is out- but that's a low priority repair.
surlyoldbill
Well-known member
reminds me I need to take my assembly out and replace all three lights. They kind of went out one by one over the last couple years.
Vent Knob Won't Turn Stuck Binding
I've read about needing to pull apart the dash to lube the cables on the vent position knob for the cabin heat. My 2004 vent selector works great. Always has. The 2006 I just purchased had the vent knob firmly stuck at the 11 o'clock position.
I really didn't want to take apart the dash. Pictures of what's inside convinced me there's nothing too critical in there.
I am lazy.
So out came the plastic trim tools. I wedged one of the tools between the dash parts in the seam just above and to the right of the stuck knob. That allowed me to stick a WD-40 red straw into the area immediately above the knob. I inserted and gave it a couple spritzes not really knowing where the stuff went.
I tried turning the knob. It wouldn't turn, but felt "less stuck". So I spritzed some more in. Now I was able to turn the knob counter clockwise, but not back clockwise. Long story short, a few more spritzes followed by some gentle working of the knob and now all seems fine.
I verified that it is actually working by feeling for air movement for the different vent level settings. Eventually I still need to pull the ATC to replace the back lights though.
I think my 2004 will benefit from a few spritzes too.
vic
Added info.
When I removed my ATC unit for lamp change the cables were fine. I think that the 2006 issue was binding plastic.
I've read about needing to pull apart the dash to lube the cables on the vent position knob for the cabin heat. My 2004 vent selector works great. Always has. The 2006 I just purchased had the vent knob firmly stuck at the 11 o'clock position.
I really didn't want to take apart the dash. Pictures of what's inside convinced me there's nothing too critical in there.
I am lazy.
So out came the plastic trim tools. I wedged one of the tools between the dash parts in the seam just above and to the right of the stuck knob. That allowed me to stick a WD-40 red straw into the area immediately above the knob. I inserted and gave it a couple spritzes not really knowing where the stuff went.
I tried turning the knob. It wouldn't turn, but felt "less stuck". So I spritzed some more in. Now I was able to turn the knob counter clockwise, but not back clockwise. Long story short, a few more spritzes followed by some gentle working of the knob and now all seems fine.
I verified that it is actually working by feeling for air movement for the different vent level settings. Eventually I still need to pull the ATC to replace the back lights though.
I think my 2004 will benefit from a few spritzes too.
vicAdded info.
When I removed my ATC unit for lamp change the cables were fine. I think that the 2006 issue was binding plastic.
I'm not so certain that the cables are always the problem.
When I purchased my 2006 used the dial was locked up tight. Using the red straw I spritzed some WD40 into the plastic dash joint above the knob. When I later disassembled the ATC for lamp change there was no sign of lube on the cables, but it did show drips down on to the plastic knob shaft. I think my 2006 problem was the plastic shaft and rotating parts getting sticky.
The above said, there have been posts where members indicated that the cables were kinked. That would point to stuck cables, or possibly binding diverter parts within the air box.
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thinice
2005 tall 140WB 160K
Mine was a little more difficult as the cable was kinked before it entered the sleeve. Had to pull the unit, straighten first, then lub. Still wasn't to big of a job. Just takes a little patients. The plastic parts that drive the operation look a bit fragile. I would not try to force anything.
misterbond10
New member
Haha! A swift punch to your dashboard fixes most ailments
seans
Member
I broke the potentiometer, but in another thread! 
I don't recall but I think it was a 10K linear taper (not audio taper.) You should be able to measure the resistance from the remaining bits or it might be marked on the side of the pot. I suppose you can find a replacement at Digikey. But I decided instead to use a full size potentiometer like the kind you can get at Radio Shack (or Digikey).
If I recall correctly, there is a large hole left when you remove the plastics, so you have to hackgineer something using sheet metal to hold the pot. There's plenty of room behind there for a full sized pot. I unsoldered and discarded the old potentiometer and used loose wires to solder up the new one. I put a big knob on it from the volume control from a home theater sound system that was acting up and had been retired. I also rewired it so that cold is counterclockwise and hot is clockwise (not crazy-backwards as it was originally designed).
The big knob covered the markings but they were pretty much useless anyway so I covered them up more (kind of, as you can see). Then I used some whiteout to put a white mark inside an indentation on the knob so I can see where it is set. The crude "C" and "H" I painted are blocked by the knob so there's no real point in painting them on.
I have access to a laser cutter now, so I might fabricate a replacement face with a keyed hole for the pot. Or, I might rip out the heater controller altogether and replace it with an Adafruit Huzzah running Arduino so I can control it from the back of the van.
I don't recall but I think it was a 10K linear taper (not audio taper.) You should be able to measure the resistance from the remaining bits or it might be marked on the side of the pot. I suppose you can find a replacement at Digikey. But I decided instead to use a full size potentiometer like the kind you can get at Radio Shack (or Digikey).
If I recall correctly, there is a large hole left when you remove the plastics, so you have to hackgineer something using sheet metal to hold the pot. There's plenty of room behind there for a full sized pot. I unsoldered and discarded the old potentiometer and used loose wires to solder up the new one. I put a big knob on it from the volume control from a home theater sound system that was acting up and had been retired. I also rewired it so that cold is counterclockwise and hot is clockwise (not crazy-backwards as it was originally designed).
The big knob covered the markings but they were pretty much useless anyway so I covered them up more (kind of, as you can see). Then I used some whiteout to put a white mark inside an indentation on the knob so I can see where it is set. The crude "C" and "H" I painted are blocked by the knob so there's no real point in painting them on.
I have access to a laser cutter now, so I might fabricate a replacement face with a keyed hole for the pot. Or, I might rip out the heater controller altogether and replace it with an Adafruit Huzzah running Arduino so I can control it from the back of the van.
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A.Hayes
Member
So I finally did this fix to correct the operation of the knob- works great now but the lights behind the temp dial and fan speed are now only working intermittently. They are usually out but seem to come on if the van has been running a while. I haven't taken it back apart to see if there is just a connector that I knocked loose, but does anyone have any suggestions what happened? If it's inside the heater control unit I probably won't bother messing with it again... although jmollers mod to get some actual floor heat is pretty appealing.
2005 LTV RV conversion on 2500 chassis....
Sent my module off to be repaired, Module Repair Pro in Cal. Two day service, the Technician even called me back to tell me that he recommended I replace the two cables that connect to the vent knob rather than just lube them. Trying to find the right part number online, I see three that I think might include them, but I only need two....
05104492AA
05104493AA
05104494AA
I thought I'd ask if anyone can confirm which two of these part numbers I should order, or if I'm even asking about the right cables, it was a bit hard to tell from the online parts diagram I found.
Thanks for any advice. roy
Sent my module off to be repaired, Module Repair Pro in Cal. Two day service, the Technician even called me back to tell me that he recommended I replace the two cables that connect to the vent knob rather than just lube them. Trying to find the right part number online, I see three that I think might include them, but I only need two....
05104492AA
05104493AA
05104494AA
I thought I'd ask if anyone can confirm which two of these part numbers I should order, or if I'm even asking about the right cables, it was a bit hard to tell from the online parts diagram I found.
Thanks for any advice. roy
autostaretx
Erratic Member
Just working from the parts catalog (available from http://aie-services-2.net/Sprinter/ ) (acrobat page 480, cat page 024-130) ,i see that:
05104492AA <-- (no specific function stated) MB number A9018330031
05104493AA <-- defroster cable ... MB number A9018330131
05104494AA <-- water valve cable ... MB A9018330231
So: wildly extrapolating: the "water valve" cable probably is not connected to the "which duct blows" knob.
((why would it be??))
--dick (who has not yet pulled his AC control panel (but the middle knob has never turned easily, even when new...))
05104492AA <-- (no specific function stated) MB number A9018330031
05104493AA <-- defroster cable ... MB number A9018330131
05104494AA <-- water valve cable ... MB A9018330231
So: wildly extrapolating: the "water valve" cable probably is not connected to the "which duct blows" knob.
((why would it be??))
--dick (who has not yet pulled his AC control panel (but the middle knob has never turned easily, even when new...))
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