Passionate about Mercedes, first car was a 1972, up graded to 1984 300D, 90's rolled around and had a blast with my 190E. The one thing I really missed was american/japenese cars had a nice feature on there A/C, you could open vents to allow air for circulation yet no blower to make you cold. always had a ruff time figuring AC and heat.
Well I moved up again, 95 S500. once again heating system frustrating me. I was sad to hear rear heat was not a standard option in this Highend Benz(who would have thought?) There is a vent in the back seat but for cool air only(i thought it was broke)manual confirms. Cold air is always blowing on your legs, the higher u turn blower to heat car the stronger that cold air gets! What i am wondering is when you change the Automatic heater valve you have a choice of parts one if you have rear heat and one with out rear heat. Is it possible to install automatic climate valve with rear heat and change/replace the vent covers with the heat dials on it? Or is it just toooo much work?

I may be wrong, but I thought they all have rear heat comming out from floor vents under the driver and passenger seats. The rear cener vent is for fresh air and you can chose to close it or adjust how much fresh air comming in.

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1991 420SEL Project Car (Completed and rides beautifully) http://www.peachparts.com/shopforum/tech-help/112321-free-1991-420sel.html
2000 BMW 740IL
2000 Integra Type R - Track Car - SOLD
2005 S2000 - Track Car
06 C230 Sport
89 560SL

from under seats the heat trickles out....not sure if vent or just comming from front floor. the center air vent only swings right or left; bumber you can't just face it up towords headliner. Yes, your right I should be able to completely close that vent but...Germans....used a pully cable system for that trap door, I can't get to it as to tighten that cable so it will close all the way, Hey, there is only so much my bobbie pin, nail file and a butter knife can fix!! I suppose I should find me a nice Mercedes man.

Are you getting full head on legs up front? I've had an issue with my 300SDL, where the driver's side diverter flap did not close and I had no heat on the driver's side front OR rear.

In case the designs are similar, and I don't know that they are, try this quick check. Feel under driver and passenger footwells for heated air flow. If they are getting heat, I'm guessing the rear should be getting trickle heat, and if they are not, I'm guessing a diverter door problem.

It might be a place to start...

Best Regards,
Jim

P.S. I assume that there is nothing under the driver or passenger front seat, like stuffed animals, etc. that is blocking the air flow....

The rear consol vent blows only cold air, close if for winter or the passengers will freeze.

If the front footwells are cold, you have a leaking servo and no heat (or a broken vac line if you have most of the air going up the windshield all the time).

If the front footwells are warm, remove the extra floor mats in the back -- they are almost always too long and usually block off the heat vents under the front seat. Remove any other accumulated odds and ends as well.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I have the same problem on my 95 s350.
And I just was thinking to go to the MB shop, since I've been dealing with this for the past two winters.
When the rear console is closed all the way down (you hear the click when it reaches all the way down) the cold air is still coming out(not as much but enough to freeze you) and the fact that the heat is coming from the rear footwells doesn't change anything because the rear passangers knees are almost frozen.
What I've been doing so far is put something on top of the rear console like my coat or something simmilar.
I would love to see this fixed if possible, and it would great if the rear console could blow hot air.
I was surprised when the rear console on my cousin's '97 e290 td was blowing hot air and a 95 w140 doesn't. Shame.

I have the same problem with a 95 s320. It was 3 degrees here last Sat night. My rear seat passengers loved the rear seat leg room but froze their butts off. Is there a way to fix the vent so it closes all the way?

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jayhawk