300SD w/ACC: no airflow in driver-side footwell

[deniss]

I had weak airflow to the driver's side footwell for a while now, and now there's nothing. The heat is working in the rest of the car, including passenger side footwell, which gets nice and toasty, while I'm freezing my feet off driving this car!

The Benz dealer said they are not sure yet how many hours of labor it would take to diagnose this, but they said it will involve taking apart some of the dash. Is this for real??

[bodyart27]

Keep in mind this is my experience with an 84 126 chassis 300sd (not sure of yours).

I suspect two area need to be checked. There is a bank / row of crossover swiches (not sure if that is the correct name) that sits on a rail right of the radio. You really need to do some console dissasembly to get to it - but that rail by your passenger's left knee / calf is controlled by electric signals from the climate control and those switches take vacuum of the common rail and diverts vacuum (sounds illogical - but you get the idea) to all the pods in the dash and panels. If the switch is bad - the pod never gets the vacuum to pull open or close the vent needed.

Next is the pods themselves. They have a diaphram in these little easter eggs that are sucked in by the vacuum. The daiphram has the arm connected to it that pulls and relases the doors that diverts airflow. If the diaphram rips - it can't pull the arm back. Most are replace only. I think one or two might be repairable.

The PITA vac pod is the one that controls the center dash (for nice A/C on your face). I think you will luck out on the location of the one for the floor vents, but I'm still at work at the moment and don't remember how much dissassembly is required.

A good site that has an amazing step by step pictorial on diagnosing the switches and location of pods and how to get to them is pindelski.com. It's a pay for site - but you'll get back what you'll learn off that site.

[deniss]

Yes, rigging the flap open sounds great right now Especially since I don't have a garage to work in and it's a bit nasty out.

I will probably take the system apart this spring... But until I can work comfortably outside, this temporary solution would be great...

[toomany MBZ]

I had the same issue. On mine it was a vent door that had failed. I propped it open, now I have air all the time. Apparently a joint had come apart not allowing the door to open, and the fan pushes the door closed.
I removed the lower kick panel, and was able to reach said door, tied a string around the device I used to prop open, just in case it fell in somewhere, so far, so good. Been almost a year. BTW, I used a spark plug!