Fresh/Recycled Air Button

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C Class
Posts: 41
Joined: Sun 24 Jun, 2012 9:22 pm
Model you own: w168

Fresh/Recycled Air Button

Post by nvrau » Mon 05 May, 2014 6:30 am

I have a pet-hate with the car always resetting the fresh/recycle air to fresh after a period of time. Has anyone attempted to change this behaviour or know of a way to disable it?

I don't care what the reasoning behind it is. I don't want fresh cold air coming in when I am trying to warm the car, as well, I don't want fresh warm air coming in when I am trying to cool the car.


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Mercedes Demigod
Posts: 5497
Joined: Thu 28 Jul, 2005 10:33 am
Model you own: w124
Location: Hawthorndene SA

Re: Fresh/Recycled Air Button

Post by Hendrik » Mon 05 May, 2014 11:43 am

Assuming the system is similar to the earlier climate control systems, you may well find that the system is smarter than you think, it does in fact block off fresh air partially when it thinks that is the requirement.

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Greg in Oz
Posts: 3221
Joined: Tue 01 Aug, 2006 10:08 pm
Model you own: I own multiple different models
Location: Sydney, Australia

Re: Fresh/Recycled Air Button

Post by Greg in Oz » Mon 05 May, 2014 12:14 pm

The HVAC system switches from recirculated air to fresh air after a period of time for very good reason. It is to prevent the passengers (and driver in particular) from becoming drowsy through breathing stale air with a high level of CO2. I can understand that you may not want to have to heat or cool fresh air, however the heater and A/C are more than capable of doing this and I believe the extra energy used doing so (compared to heating or cooling recirculated air) will be minimal in comparison to the energy used propelling the vehicle. I also believe most heat loss and gain in a motor vehicle will be through the metal panels and glass rather than through non-recirculated airflow. The recirculate setting is really only intended for use when the air outside is very dusty or smelly and the assumption is that the conditions won't remain that way for more than a short period of time. Personally, I hate travelling in a vehicle with the air set to recirculate or the outside air shut off.
107023 - 350SLC: 1973, 3sp auto, icon gold, parchment MBtex (sold July 2012 after 29 years ownership)
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124090 - 300TE: 1990, 4sp auto, arctic white, cream-beige MBtex
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201024 - 190E-2.0: 1985, 5sp manual, black, black MBtex
201028 - 190E-2.3 Sportline: 1990, 5sp manual, arctic white, blue leather
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