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92 300SE
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21 Posts
Discussion Starter · #1 ·
OK, I have read the owner's manual on this 3 or 4 times and I still don't get it? What are the two buttons between the center vents, one is red and the other blue. The manual said push the blue button on during heating mode (you want cooled air in heating mode?). Then it states push the red button on during cooling mode (fresh air seems to be red?). What is the purpose of these buttons? Today, I pushed the red button on during cooling mode and it seemed to do nothing other than cut my air flow down? Any light you guys can shed would be great!
 

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1994 S320 SWB
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703 Posts
i normally push the red one while i'm running heat and sometimes ill push the blue one if im running AC...i never truely bothered to see what they did i just thought it was what you were supposed to do haha
 

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1996 S320 (Kuro) 1998 S600 (Weiss)
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2,885 Posts
From what I understood with the Red button pushed it runs the airflow past/through the engine before reaching the passenger compartment whereas the Blue button was the same airflow bypassing the engine.
 

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1995 Silver S-320
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681 Posts
pressing the red button shuts off the hot air which can be manually done if clamping a hose under the right side of the hood if facing the grill. But instead a internal valve or some other kind of mechanism does it i believe when the button is on. and the leaves just the cool air.

And pushing the blue button cuts off the flow of the cool air and only allows the heated air.

Simple as that from what i understood in using them and a little experimentation i did when the A/C went.
 

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2016 E350 4matic Luxury Sedan, 2011 E350 Avant Garde Cabriolet
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1,951 Posts
Actually you have it backwards.

RED=Heat

BLUE=cooled air.

You can run it without pushing the buttons. They just increase the airflow to the vents during A/C season.
 

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1996 S320 (Kuro) 1998 S600 (Weiss)
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2,885 Posts
DaimlerChrysler said:
Actually you have it backwards.

RED=Heat

BLUE=cooled air.

You can run it without pushing the buttons. They just increase the airflow to the vents during A/C season.
So they increase the airflow at the current tempurature only? Or they add either hot or cold (depending whether of course you press blue for cold or red for hot)?
 

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2016 E350 4matic Luxury Sedan, 2011 E350 Avant Garde Cabriolet
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1,951 Posts
I think that the red/blue buttons are a mystery to rival the Egyptian pyramids!

From what I understand from the dealer the red button locks the vents into heat mode. The air is directed to underneath the dash, front seats and doors.

The blue button locks the system into AC/vent mode. All air is directed through the dash vents.

The air coming from the rear vent between the front seats is not temperature regulated unless you have a 600 series with the rear climate control (I believe it was standard on the 600SEL/S600 and optional on other models).

For fully automatic operation you can operate the system without pushing the buttons. The air doesn't circulate as well on AC/vent.

PC MAHER is better at this than I am and I think that he gave a detailed description somewhere on the board, but I hope that this helps you out!
 

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1997 S600 (sold)
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4,660 Posts
And one more function... You cannot manually direct air to the center vent (when in manual control mode) unless one of the buttons is pressed. At least, that is the way it is on my 1997 model with the digital display climate control head unit. The control unit shows arrow indicators telling you which vents are selected in manual mode. The center vent indicator does not light, and you get no air unless one of the buttons is pressed.

Brett
 
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