I find the recirculation on this car (and probably every other Mercedes) to be extremely annoying. It will not stay on if you activate it. I assume there is no fix for this and it is operating by design. If I have the AC on or OFF, the recirculation will only stay on for like 6-7 minutes and then revert to bringing outside air in. I can totally understand this from a design standpoint, because having only recirculated air will deteriorate the air quality inside the car after long periods of time. However, with the recent fires in CA, and the subsequent poor smoky air quality outside, it is really annoying to constantly have to press the button, and have it revert back, bringing smoky air inside the car. I have driven other cars that either stay on, or have.a way to have it stay on such as holding down the button. /rant

 

Good reason to rant. I've had thie 'problem' with other Mercedes NANNY cars and dislike it. Porsche does not have this 'problem' nor did a Jag XJL I had. But Mercedes is the top one NANNY CAR. and for unknown reasons Mercedes buyers like Nanny cars.

Bottom line from the Nanny owners is that this 'feature' will save your life and or keep your windshield from fogging up. The same people probably want self driving cars (dodo heads imho).

 

i think it also has to do with the auto on/off function when you come to a stop. when the engine off function kicks in (to save gas) i think it triggers the re circulation to cancel out.

 

I've had it go off without the auto stop/start function occurring.

 

IMO it is a safety issue. For years the recirculate function on GM vehicles mixed about 50% fresh air with recirculated air.

 

There are times when even doing a mix is a safety issue. If you have sensitive allergies it can be a hazard. Try sneezing a dozen times in a row while in heavy traffic.

 

This is a safety function to prevent excess co2 from building up in the cabin.

 

I had a Tacoma that would turn it off automatically after a while. I found out that by holding the button for approx 20 seconds it would stay on recirculate. Tried it on my 18 AMG but it didn't work.

 

This seems the case in most Mercedes cars/SUVs.

Sometimes when I am sitting in traffic, I want to limit the exhaust intskefintake other cars and push the "recirculation" button. But after a while, it goes off on its own.

 

Yeah. I had a XJL and if you held the Recirculation button for a few moments it would remain in recirculation. Mercedes is a NANNY car way too much imho.

I've a 2017 Porsche Panamera 4S and there is a haptic switch on the center console and if you push it, then the recirculation remains in recirculation. Plus it has a switch on the overhead console that will eliminate the sound/noise if you get too close to your garage door (that happens each and every time. NOT too close at all). Two good examples of cars not being Nanny cars. Tesla is beyond hope and should be scuttled.......if I didn't have a bunch of it I bought on March 17th.

 

CO poisoning is serious stuff

 

The issue I also have is that there is no smog sensor on our cars, like there is on other luxury makes. A lot of cars have an Auto setting fo recirculation when it senses particulates or smog, but that doesn't seem to be the case here.

 

I have never heard of that one..

What car today has it I wanna check out their website?

 

https://www.lexus.com/pdf/service/ISC_LPS.pdf

 

Yah, every Lexus in the recent years have it. That was the brand I was thinking since I previously owned a few.

 

interesting and states for use only on that one car....IS350C

Never owned a Lexus....
After a little bit of internet searching seems to be only a LExus feature

 

CO is a threat, but I believe the other overriding engineering factor for non-continuous recirculation is condensation build-up in the A/C passages. Without literally 'fresh air' into the system, there is high risk of constant standing water and subsequent mold formation in the evaporator "box" (the cooler part), especially if the car is parked for extended periods if running constantly in recirculation mode. It can be understood why recent designs do not hold recirculation on permanently.

OTH, I hear you about what a PITA the fires are on all kinds of levels. Such large, continuous amounts of smoke particulate is a very low probability event, and understandablly something not presently a design criteria given the above considerations. Sort of a situation where one cannot look at their their cake and eat it at the same time. Maybe Mercedes will read this thread and change their firmware to allow an override on the recirculation button.

There is a dry paper filter on the air inlet under the hood and a second, thick, high quality particulate filter in the air pathway. If you have allergies, I believe there are slightly more expensive, special active carbon filters available from MANN or other German OEM suppliers. This could be changed every 3-6 months instead of recommended 12 month interval. Continuous fire smoke excepted, this would be a better solution considering the car A/C system and your respiratory system together. Also, might it be a good idea to learn how to change that passenger footwell large filter, certainly once the smoke is subsided, if not evert couple weeks during??? In heavy smoke areas it would not be a case of over-kill, that is for sure.

As an aside, I habitually turn off the A/C and set the fan to high when I am within 2-3 km any destination anytime the car will be sitting for more than a few hours, especially in a small garage. This purges the evaporator air box of condensation and dries out the internals. There is often a substantial amount of liquid water blown out via the drain holes using this technique, especially if the ambient humidity is high to begin with. Prevents any musty smells from developing over the period of ownership.

 

That poster's attachment is for the Lexus personalization settings, and they are specific to each model. That one was an example from the IS convertible (no longer in production) but each model had an attachment like that, and each model has a sensor for smog.

Genesis is another brand that has this: https://genesisowners.com/genesis-fo...l-system.2949/

Porsche seems to have it too: https://www.macanforum.com/threads/a...ulation.72322/

I didn't search for every brand, but a simple google search for ["brand" automatic air recirculation smog] gave me those results

 

yes i did the same and that was the only thing that popped up during my 15 second search ;-)