Oh. Woops. I'm glad you asked. I totally forgot to explain that. I edited the very first paragraph to explain why... But I'll add it here too.

Basically, the primary reason for wanting control over the vents is that in heating mode, by design, the center vents do not operate. When my hands are cold, I can warm one up with the side dash vent, but not the other hand. Turning on the center vent solves this problem. Also, sometimes the heat on my feet is too much. Furthermore, in cooling mode, only the center vents operate, not the footwells. I'd rather just have a switch.

hmmmmm

The standard design will chuck cabin temperature regulated heat out the footwells / side vents / screen vents depending on where you set the position of the right hand control.

The amount of heat output is regulated by the thermostat for each side, and depends on cabin temp vs thermostat temp, and of course fan speed.

The side vent is there, not to "warm your hands" but to provide a convenience store like hot air curtain so you can drive with the window cracked down (smokers) and not get the cabin cold.

If you have one cold hand, then your cabin temperature is not up to spec, so you have a separate thermostatic control problem that this mod is not going to address.

My W124 has one of the best heating systems ever fitted to a car, I get warm air within 400 yards of an overnight cold start, and within 800 yards the cabin heating system is basically up to speed.

this doesn't apply to the write-up presented here. you have a different heating system, we have ACC in north america. two very different systems working in very different ways. some similar components but the control of the systems is completely different. i have a euro 124 and i know what you're talking about but it doesn't apply at all to what the OP is trying to accomplish.

it's an awesome write-up and incredible amount of thinking and design went into this. i wonder also 'why' but the answer in this case must be 'because i can'. even if i don't understand why someone would go to such lengths, and rationalize it for warming their hands - i warm my hands on the vents too, it's cold up here in toronto, i would never go to such lengths for such a mundane 'improvement'.

the fact is that someone with limited ability to think this concept through could simply follow these instructions and achieve the results perfectly. it's no mean feat to put this together - i say 'well done'

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punkinfair

Now THAT is interesting....

MB USA seems to be on another planet in many ways, not least of which is calling everything a 300D

Wow!! Nice write up.

Makes me wish I owned one just so I could try it.

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Experience : what you receive 3 seconds after you really needed it !!



86 300SDL 387,000? Motor committed suicide
81 300SD 214,000 "new" 132,000 motor
83 300SD 212,000 parts car
83 300SD 147,000

91 F700 5.9 cummins 5spd eaton 298,000
66 AMC rambler American 2dr auto 108,000
95 Chevy 3/4 ton auto 160,000
03 Toyota 4runner 180,000 wifes

First, superb job, including the documentation.

Second, why don't they make heated steering wheel, they make heated seats which my ass does not need warming, but heated steering wheel would be nice.

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2010 ML350 Bluetec
2012 Mustang Convertible