Air Recirculation system broken actuator parts - DIY fixes

Jodean

Member
mine just popped out again, still not broken just slipped out somehow again, i didnt fix it, i wired it closed, no need for fresh air on this thing!

If i realy need fresh air, ill open hood and pull wire off.
 

220629

Well-known member
??? the door is normally open.....pushing the button closes it

so said conversion door would normally be closed, as in key off, better for your rodent idea!
That may be correct.

I might have been thinking about when the actuator linkage assembly is broken which allows the diverter door to swing in the breeze finding some mid position. In that case there is definitely easier rodent access.

:cheers: vic
 

SAM_PGA

New member
mine just popped out again, still not broken just slipped out somehow again, i didnt fix it, i wired it closed, no need for fresh air on this thing!

If i realy need fresh air, ill open hood and pull wire off.
I'm going to use the wedge or wire my recirc door shut as well. Can anyone please post a pic of how they wired the door shut? I'm sure its pretty simple just curious as to what works.

Thanks!
 

SAM_PGA

New member
After turning on the engine and turning on air recir, I used a wire (from a wire hanger) and hooked one end around the pivot/door lever, ran the wire forwards and underneath the air box, wrapped around the air box counter clockwise back to the door lever (starting point), snipped and trim the length of the excess about 3" past the pivot, worked the tail end underneath the pivot and bent the excess wire back hooking the door pivot once again. The wire is pulling forward and upwards and after turning the air recirc off, the recirc door still has a good seal.

THEN I removed the cabin air filter and clean the inside (of what I could reach). Now with the top vents closed and the flow switch on dash only I can feel the air blowing all the way to the back of my concept sales van. The amount of air on high coming from the vents is ridiculously good!!! Fingers crossed it still works well during our heat wave in Tennessee.
 

addy6

New member
Re: Air Recirculation system broken actuator parts

Since I wrote this, the belcrank on mine broke. Dodge, MB or Valeo (that's who makes the air distribution system) do not offer the small bits and piece parts. By happenstance, I found a company that 3D printed a replacement belcrank for me. It's a perfect fit and has been installed for several months without any problems.
Working on it isn't hard, but it is time consuming because you are mostly working by feel due to the location of the parts.

The actuator is held in by two screws, a vacuum line and an electrical connector. Remove the fasteners first, then you will have better access to the actuator to remove the connector and vacuum line.
The belcrank is notched on the actuator end at a location that keeps it from becoming disengaged.
Here is how I installed replacement belcrank and actuator:

The actuator has to be fully retracted during installation to give you the necessary room. I used safety wire to keep it fully retracted until it is fully installed and the flapper arm is installed onto the belcrank pin. The full retract position is also the recirculation position - flapper door closed.

Install the belcrank onto the actuator end. Carefully install the belcrank/actuator assembly onto the belcrank shaft. Do not try to fit the pin into the flapper lever - it gets installed as the last step.

After the belcrank is in place on the shaft, install the actuator fasteners, connector and vacuum lines.

Using a long screwdriver, long thin yard stick - push/deflect/slightly bend the flapper lever enough to fit over the pin on the belcrank. I would recommend applying heat from a hair dryer to make it more pliable.
If I could have easily removed the flapper lever, I would have. I believe it is held into the flapper door by lock tabs, but I didn't want to risk any damage.

Remove the safety wire from the actuator and test operation.

Hope this helps.

Bruce
Bruce,

I was wondering how your replacement belcrank is holding up and could you provide a contact for the 3D company that printed yours?

Thanks,

addy6
 
I think the part is on thingiverse, I have seen a few sprinter HVAC items on there. They also provide a printing service, I used a couple of them before I got my 3D printer.
 

doug022984

Sporadic Member Since 2015
I thought I'd toss in my low-cost repair for this lever / belcrank or whatever you want to call it. Mine was also broken and looked almost identical to bc339's in post #12 of this thread. I didn't want to spend $50 on a 3D-printed one nor did I want to whittle one from a block of Delrin I had laying around (although I did think about it). I was inspired by Aqua Puttana's mention of using a nail. I mic'd the OD of the good pin at exactly 5.0 mm (knowing Mercedes would use metric everything) or 0.196". I wanted something close to that diameter but couldn't find any nails that size and didn't have any M5 metric bolts with shanks laying around. A #10 bolt shank is 0.145" diameter, so a little small. I settled on a 3/16" diameter (0.187") drive nail anchor (pictured) for $0.33 at ACE hardware.

Then I had to drill a 3/16" hole in the arm. I didn't trust myself using a drill accurately without messing up, so I used a 3/16" endmill since I'm fortunate enough to have access to a machine shop.

Hacksaw off both the ends of the drive nail anchor after measuring the length you need, leaving the head on; insert it in the hole from the back side and then Q-bond the $%&@ out of it for reinforcement. You're left with a pin that's stronger than the plastic one on the other side. If you've never used or heard of Q-Bond, GET IT! I haven't found anything better for repairing/reinforcing little plastic auto parts.
UPDATE: after almost 4 years of use, my bellcrank repair was still functioning, but since I had to remove my ventilation housing for another repair, I inspected it and noticed a lot of the superglue Qbond material was gone and the pin was loose. I'm now trying 2 part epoxy to hold the pin in place, which will hopefully last longer.

ALSO A TIP (since it wasn't obvious to me the first time): my original repair was done trying to work my hands in on the side of the ventilation housing with it installed in the van. This required some blind work, lots of hours and swearing. Having recently removed the ventilation housing, I recommend doing this for any repairs to the recirc door mechanism. Contrary to what the service manual appears to say, the ventilation housing can be removed simply with 5 nuts and a couple electrical plugs. The wiper fluid reservoir, all refrigerant lines, coolant lines, and even the turbo heat shield can all remain in place to remove the ventilation housing and then working on the recirc door mechanism is so much easier.
 

gilee

2006 Sprinter 2500 Camper
UPDATE: after almost 4 years of use, my bellcrank repair was still functioning, but since I had to remove my ventilation housing for another repair, I inspected it and noticed a lot of the superglue Qbond material was gone and the pin was loose. I'm now trying 2 part epoxy to hold the pin in place, which will hopefully last longer.

ALSO A TIP (since it wasn't obvious to me the first time): my original repair was done trying to work my hands in on the side of the ventilation housing with it installed in the van. This required some blind work, lots of hours and swearing. Having recently removed the ventilation housing, I recommend doing this for any repairs to the recirc door mechanism. Contrary to what the service manual appears to say, the ventilation housing can be removed simply with 5 nuts and a couple electrical plugs. The wiper fluid reservoir, all refrigerant lines, coolant lines, and even the turbo heat shield can all remain in place to remove the ventilation housing and then working on the recirc door mechanism is so much easier.
Hi Doug, I am also having problem with my recirculation, and will need to remove the housing to fix the recirc door mechanism.
It is great to see your TIP, and looking at the service manual (attached below), it only shows 4 nuts.
Thanks again!
 

Attachments

owner

Oz '03 316CDI LWB ex-Ambo Patient Transport
Has anyone thought about somehow reversing the bellcrank/actuator/spring mechanism so that the door is open when the button is pressed, and is in recirc by default? I though about doing this by swapping over the actuator to bellcrank pivot. It would require a slight re-mounting of the actuator, but other than that it should just work*.
I have actually done this now, and it has been working fine for 6 months. So its solidly in recirc mode all the time even with the engine off. In fresh air mode it opens the flap blade about an inch, so its not a true 100% fresh air solution, but it works for me.

I guess it could be made to work better, because all I did was hack off some plastic and re-mount the vacuum actuator so it worked in reverse. Crude but totally effective for want I wanted.
 

220629

Well-known member
...

I guess it could be made to work better, because all I did was hack off some plastic and re-mount the vacuum actuator so it worked in reverse. Crude but totally effective for want I wanted.
Any chance for a picture(s)? Others may want to copy what you did.

:cheers: vic
 

lindenengineering

Well-known member
The whole component is not stocked in the USA anymore by MB parts divs.
It is still available through MB parts per special order from Germany.
The current price is $185.

We still have a few good used take offs in stock for our shop use.
Not exactly a nice jib to R,n, R at about 3,5 hours of shop time required.
Dennis
 

ECU

2006 T1n 118 Sprinter
the vents up above the radio are not heat. They bring in outside air, AC if the AC is on. But not heat.
 

DIYRV2020

Active member
Can the linkage showed below be taken out without removing the vacuum actuator? This part on my Sprinter is broken too, I am thinking about taking it out to repair it using epoxy or plastic glue. Maybe loosening the screws that hold the actuator in place would creat enough room to pop this linkage part out.

And to install it, just simply push it in? is there something it connects to needs to be held in place from inside the air box?

7368C600-28FC-408D-8D2A-D4AD963DF4CF.jpeg
 

WerkSpace

Member
My recirc door bellcrank hinge pin completely broke off from the plastic HVAC duct.
There are only five nuts to remove this duct, plus three cables and a vacuum line.
The three cables are the blower motor, the vacuum actuator and the blower speed resistor.
I dismantled the HVAC duct even further, so that I could access the part that needed repair.

I used a butane pocket torch and a flat blade screwdriver to weld the bellcrank pivot back into place.
The torch was set to low and I just barely touched the plastic each time.
Then, I used a screwdriver to shape the melted plastic.
The process was simple and it worked.

When I got done with my DIY plastic welding job,
I sanded the DIY weld inside of duct, so the the recirc door would move smoothly open and closed.

When all of this was done, I asked myself why this piece broke in the first place?
I came to the conclusion that the bellcrank hinge pin had no upper support and this caused the duct to flex.
Whenever the vacuum actuator pushed or pulled on the bellcrank, the duct was flexing underneath the bellcrank pivot.

So, I decided to install a 1" X 1" piece of aluminum angle to give the top of the bellcrank pivot proper support.
I drilled a 1/8" hole thru the bellcrank and pivot, then installed a machine screw to hold it all together.
I used two 1/8" rivets to fasten the aluminum angle to the plastic support wall.

I've included a couple of photos of the finished job.
I'm happy to report that the surgery went well and patient is recovering just fine. :)

Recirc door hinge repair.jpg
 

DIYRV2020

Active member
I think this air box housing is definitely a marginal design, the wall is just too thin. Mine has the same problem, there is a crack around the base of the hinge pin which causes it to wiggle a bit when under force, I believe that was the reason why the linkage broke on mine. I used the approach showed in post #24, but I glued a piece a plastic instead of wood and it works and should last a long time.
 
A bit off topic, but has anyone mouse proofed this air box opening in the engine compartment without significantly sacrificing air flow? I have no rodent infestations, as far as I know, but have used hot paper tape on the wiring and a few pellets here and there of mouse 'deterrent' where it won't blowoff or get sucked in when on the road.
 

WerkSpace

Member
A bit off topic, but has anyone mouse proofed this air box opening in the engine compartment without significantly sacrificing air flow? I have no rodent infestations, as far as I know, but have used hot paper tape on the wiring and a few pellets here and there of mouse 'deterrent' where it won't blowoff or get sucked in when on the road.
 

WerkSpace

Member
I saw your post before trying to fix my issue, but I got it in my head that I could weld this plastic with a butane pocket torch and a flat blade screwdriver. My thinking at the time, was that this part is borderline unrepairable, so I went for broke and gave it a try. The duct plastic actually welds very nice. I was surprised. Here's a YouTube video that I found that sort of shows what I did with my butane pocket torch.

My second option was to try mixing some plastic with MEK and making a putty. I've seen this done in the aviation world.

Your bellcrank photo looks like it could use the 1" X 1" aluminum angle fix, to keep the bellcrank perfectly vertical. When the bellcrank gets off center, it puts extra stress on the actuator and the lower pivot mount.

I wish that a company like Mercedes would build things to last. It almost seems like a lot of their products have been designed to fail. This is how an economy is created. People keep buying the same old parts that are prone to break. If something breaks, I want to know why it broke and try to repair it, so that it will never break again. I don't want to reward bad engineering by constantly purchasing parts that I know will fail again.

I think this air box housing is definitely a marginal design, the wall is just too thin. Mine has the same problem, there is a crack around the base of the hinge pin which causes it to wiggle a bit when under force, I believe that was the reason why the linkage broke on mine. I used the approach showed in post #24, but I glued a piece a plastic instead of wood and it works and should last a long time.
 
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