99 ML320 Recirc Air
 

I use the recirc most of the time in Texas, just to keep out as much pollen and dust as possible. That is a second value in the Recirc function. I do not put windows down when I start up, just let the A/C do the job and the Recirc stays on continuously in the Summer in my ML -- which is the car I use the most. I don't use recirc in my other cars most of the time.

I thought the idea behind this was if the cabin temp sensor is reading close to set point than it will allow outside air in. If it is above than it closes it to reach setpoint quicker.
I dont remember what temp it will start to mix.
I close mine after this point when nessasssary. Trucks ,farms ,ect

Joe

Wisely designed?
 

I don't know about the winter air thing. Here in the south, the air outside is much more humid than we want, especially during this hot summer. I could see in the winter where fresh outdoor air might be good to get, but I doubt the engineers took any of that into account, seeing as how they designed a terrible a/c system. People who drive a Toyota Tercel drive more comfortably in the summer heat than most in a MB owners do.

And for those with fogged up windows in the winter, they need only to use Windex on the inside of their windows; that'll clean 'em. :)

Same question here, my 88 TE does not react at all to activation of the Re-Circ button. No noise or change in blower noise. On the other hand my 95 Saab 900S blows substantially harder and you can here the actuator moving when the recirc button is engaged.

The TE has had all the vac pods replaced while doing the evap. replacement 3years ago so I am confident the vac system is working. I just think it is a poorly designed A/C system.

I am in the market for a replacement wagon and frankly after driving a few 210 wagons (01-03) I am not sure MB has updated the A/C system at all. Not all that impressed with the new system in comparision to my car, 14 years it's senior. With all the interior space of the wagon you would think MB would have come up with a system for heating/cooling the rear space of the car other than the tiny vent at the rear of the center console (why cool the inside of the console? what engineer came up with that waste of time?). I specifically tested the Recirc button on three different 210 wagons with the same apparent result as the TE.

Living in the Lowcountry of SC where 90 degree/90% humidity is common A/C function is a big concern.

My two cents for what its worth.

EJC

Why only 20 minutes?
 

Why does the manual (from memory), say to only use it for 20 minutes?

1991 300d, 90k

Mine does work, but doesn't change the sound either. Just the nature of the beast.

1. To supply fresh air, rather than stale recycled air.

2. To prevent interior window fogging in the winter due to exhaled moisture hitting cold windows.

Use of Recirculate feature depends on the car model
 

My ML manual does not say that this feature should only be used for 20 minutes. Also, I believe a certain amount of outside air does get into the system also; not sure of that. Again, in Dallas, I use that feature all the time on the ML to keep out the millions of pollen particles that are in the air most of time.

My 420SEL and 300CE Recirc mode controls
 

Owners manuals for these two cars (which have similar systems in many areas) say that recirc will come on automatically if outside temp is above/below certain temps and that the recirc will shut off after a period of time; roughly 30 minutes ..... each car model and era seems to be a little different .... BC