willmayo20

I just recently purchased a 2001 C320 for my wife that suffers from only receiving cold air from the footwell vents. When the temperature is increased, the air still blows cold. When the air distribution is adjusted, nothing happens at all. I don't hear any kind of clicking sound at all (or anything for that matter). I've tried the defrost+recirc reset and it just keeps on running.

Am I looking at an issue with just the stepper motors? Or is something else going on here? Everything I've read in regards to the stepper motors never mentions anything about not being able to get a temperature change, yet I see that there are motors that adjust the hot/cold air mixture.

Any ideas? I plan on ripping the interior apart tonight. I'm debating whether I should stop by the dealer on the way home to pick up their 2 linkage packages they have on hand...

edit: no difference from driver to passenger side.

willmayo20

bump? anyone?

DarthBudice

What happens when you re-sync the HVAC system?
Does the system switch between cold and warm during the process?

Can you describe the outside ambient temperature, what happens when the temp dials are cranked to full heat, and do you have a sunroof that is open?

I replaced my own footwell lever and I know the HVAC system temp controls
act differently when the sunroof is open and the temps are lower.

hanknum

I have a lot of these same symptoms in my '02 C320. I have the digital controls. The control to direct it to dash/front/lower vents does not seem to make any difference. No matter what the setting, it still comes out of all the vents. Also, adjusting the temp doesn't seem to make any difference either. I either have it on or turn it off with the EC button. But, after I press the EC button, it still sends out cold air for another 10-15 minutes. I did have a friend at an independant scan the HVAC system and he said there were multiple faults. He cleared them, but it did not seem to make any difference. Please let me know what you find out.

DarthBudice

Are all vents open at once possible?
I just don't see this happening unless there are that many broken HVAC levers...

When I switch to economy mode, I notice 'conditioned' air for a good 5-10 minutes as well - I believe this expected behavior.

Anybody else have ideas? *cough Glyn cough*

willmayo20

When re-syncing, nothing happens at all. No change in temp, air distribution, nothing.

I've tried cranking it to full heat during the cooler night temperaturs (~50 degrees) and still no warm air. I've never tried with the sunroof open.

Air just comes out in the footwells, and it's always cold.

mleskovar

If the re sync continues forever without stopping then that's an indication that something is wrong with the stepper motor(s)/flap(s). Just from your symptom though it sounds like you have the classic broken linkages. There's a good DIY writeup in this forum to help you through the R&R process.

willmayo20

That's what I'm thinking too. Would it be safe to buy a single 3-pack of linkage arms from the dealer or should I buy more? What about the motors themselves?

I've read there's a valve in the engine compartment that regulates the flow of coolant through the heater core, I was just concerned that there may be an issue there due to the lack of warm air...

hanknum

Can you describe the procedure to re-sync or provide a link? Also, can you provide the link to the R&R?

Thanks

SeaCoupe

I'm right there with you.

I get my A/C to all of the vents and particularly to the footwells.

I'm going to follow along on this. Though having just taken apart and repaired the console and the arm rest, I'm in no rush to get into the dash.

Ed

mleskovar

https://mbworld.org/forums/c-class-w...g-hissing.html
https://mbworld.org/forums/c-class-w...ost-works.html

Search is your friend.....

mleskovar

The motors do go out but usually it's the links that break. I don't know what's in the link packages, I just bought the links when I did mine.

Could be, but I haven't heard of one actually going out yet. You'll need to address the stepper motor/linkage problem first anyway.

willmayo20

UPDATE: I finally ripped apart the dash to find a single actuator arm broken. It was the arm on the right footwell motor. This arm being broken caused the entire HVAC system to lose all adjustability, including temperature regulation and air distribution.

Hopefully this will help someone else now or in the future.

Thanks for all the replies everyone.

mleskovar

I hope you replaced both the left and right actuators.....

willmayo20

The left was already replaced with a previously updated version. I replaced it anyway, yes. I'm not particularly interested in doing this job ever again. It wasn't much fun. Only needed three tools though

kentfarmer

My inlaws have a 2003 c240 with the common ticking noise in dash, after cussing MB I finally found that the mode actuator was the culprit. Looking up throuh the floor vent with a flashlight I can see the flaps moving going from floor to i think upper vents and back to the floor before the noise starts. My question is can resyncing the actuators help this concern or will replacement be necessary. Any help would be greatly appreciated