Force recirculation to stay on?

Discussion in 'MINI Cooper SE' started by Carsten Haase, Aug 30, 2021.

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  1. Carsten Haase

    Carsten Haase Well-Known Member

    It's been smoky here in Oregon for a while now but this morning was exceptionally bad with an AQI of around 300.

    The air in my garage (and in my car) was still relatively clean from last night so I turned on recirculation before I left. A couple of minutes later I noticed a smoky smell and when I looked down at the recirculation button it was off. Turned it back on and the same thing happened again a couple of minutes later.

    This doesn't happen when it's hot out so I think it's something to do with the heater running, maybe humidity control? I'd rather it be humid than horribly smoky...

    Has anyone else experienced this? Is there any way to override the auto HVAC setting and just run the fan?
     
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  3. insightman

    insightman Well-Known Member

    Whenever I wonder about the behavior of my SE's controls and that behavior isn't discussed in the Owners Manual, I google for the same info about BMWs. Here's a BMW forum thread about the recirculation button shutting off when it feels like it. Unfortunately, there is no solution described, just confirmation that BMW designed it that way.
     
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  4. Carsten Haase

    Carsten Haase Well-Known Member

    Thanks! I guess I was just being lazy and should have done a bit more searching myself.

    I really hate when manufacturers think they know better than their uses and force choices. No matter how much market research they do, they will never consider all use cases...

    This is the only reason I will never buy an iPhone but I guess I should have expected the same behavior from BMW.
     
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  5. quietlyspinach

    quietlyspinach Active Member

    I believe you can change this behavior using Bimmercode. I haven't personally done so on my car, but I did see it and it appears to do what you want - "Automatic Air Recirculation" - enables/disables the Automatic Air Recirculation function.

    EDIT: There appears to be a companion setting called "Air circulation setting memory" - "Enable/disable storing of the air circulation setting. If this function is active, the last used air circulation setting will be restored during the next start of the car."

    So you'd probably have to set that one to Active and set the Automatic Air Recirculation to Not Active to make sure the car doesn't change anything.
     
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  6. Carsten Haase

    Carsten Haase Well-Known Member

    From what I found reading more about how BMW handles this, the automatic air recirculation is the computer opening/closing the recirculation flap based on an air contamination sensor which I don't think the MINI has? Those BMWs typically have two LEDs on the recirc button (off is outside air, one LED is automatic, two LEDs is force recirc).

    I'll definitely look into those BimmerCode options and see if they truly do keep the car on recirculation but I'm pretty sure they do not defeat the auto-disable timer.
     
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  8. polyphonic

    polyphonic Well-Known Member

    That's what I read too - but it NEVER kicked on or stayed on, even when the outside air was terrible. In my car recirc stays on for 5-10 minutes in the winter time, and a lot longer for summer and fall. Not sure what's guiding the decision making (temperature, humidity?).
     
  9. Puppethead

    Puppethead Well-Known Member

    In an SE, seriously? Mine won't stay on for more than 15 seconds.
     
  10. ColdCase

    ColdCase Active Member

    Its been talked about here, maybe two months ago, in terms of following a smokey diesel truck. There wasn't anyway to extend recirc besides hitting the button again and again. Annoying when following that truck. Someone was going to look at Bimmercode but the thread just died, I think, without resolution. My 2022 is 5 to 10 minutes more or less.
     
  11. polyphonic

    polyphonic Well-Known Member

    I would put a little poop emoji sticker on the button and call it "pedestrian fart defense mode." :p

    Over the past couple days I monitored my recirc and it has not turned off on its own. I wonder if your sensor is broken?
     
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  13. Carsten Haase

    Carsten Haase Well-Known Member

    I think the recirc disable timer is completely dependent on outside air temp... It was 40F this morning and mine also wouldn't stay on for more than 15 seconds.

    The previous morning was around 45F and it would stay on for at least a couple of minutes
     
  14. Novadar

    Novadar Active Member

    Brrr. 40F on September 1st. Lol. I've been living in Texas for too long. I grew up in Virginia but even 40F in September was unthinkable there.
     
  15. Puppethead

    Puppethead Well-Known Member

    I tested yesterday with temperatures in the high 60s, shuts off after 15 seconds or so.
     
  16. Carsten Haase

    Carsten Haase Well-Known Member

    I guess not outside temperature then... What's your HVAC set to? Mine is 72F and the lowest fan speed. Maybe the timer is based on how much the heater is running?

    Staying on for 10 or so minutes was ok for dealing with a temporarily smelly outside but 15 seconds is useless.
     
  17. Puppethead

    Puppethead Well-Known Member

    Mine was set about the same, slightly higher fan speed.
     
  18. Carsten Haase

    Carsten Haase Well-Known Member

    Maybe the MINI does have some sort of air quality sensor...

    The only differences I can think of between this morning with the 15 second turn off and Monday morning with the ~10 minute turn off are 5deg colder temp and cleaner air
     
  19. Puppethead

    Puppethead Well-Known Member

    I did another test on my home commute, the recirculation stayed on the entire trip (40+ miles, over an hour). I don't know what magic is behind it, maybe it has to run for short periods for a number of times before it works normally?

    Here are the environmental conditions during my test:

    Temperature: 80 ºF
    Dew Point: 54 ºF
    AQI: 32
    A/C: Automatic, 74 ºF, fan speed medium low
     
  20. Carsten Haase

    Carsten Haase Well-Known Member

    I've found that recirculation will stay on forever as long as the set HVAC temperature is less than the outside temperature (the AC is running). Once the heater comes into play it starts turning off whenever it feels like it.

    My next experiment will be changed to manual control and making sure the fan is only blowing out of the front/feet vents. I know my wife's car will disable recirculation when the fan is in defrost mode (pointed at the windshield) so maybe the automatic control is periodically switching to defrost?
     
  21. Carsten Haase

    Carsten Haase Well-Known Member

    No luck with manual fan control. No matter what vent combination was used, recirc would turn off after 15s. Nothing to do with the defrost vent.

    I miss the manual HVAC sliders in my Miata...
     
  22. ColdCase

    ColdCase Active Member

    Its possible the AC goes into max mode when the difference in indicated interior temperature is much more than the desired set point. Or when the outside temp is high, or when there is a lot of sun. AC max modes typically use recirculate and, in some conditions, don't increase fan speeds. If BMW uses the same fresh air strategy as other car makers, recirculate will cycle off now and then to let fresh air in, the change in vent temperatures that result seems to annoy drivers.

    Long term recirculate when its cold enough out tends to lead to condensation and frost on interior windows. I dunno how effective the Mini is in keeping the interior of windows free of condensation and frost. If its weak I could understand a recirc limit, but 15 seconds seems too short.
     
    Last edited: Sep 3, 2021
  23. Puppethead

    Puppethead Well-Known Member

    There's a separate AC Max control. When I did my test that was off, but my recirculation stayed on until I stopped the car. @Carsten Haase I suggest trying it a few more times (maybe separate drives) and see if it eventually stays on. Every time I tried my recirculation it would shut off after 15 seconds or so, until this last time when it stayed on indefinitely. Maybe there's a "burn-in" period of some sort after being newly-built? Could there be some sort of residue inside that's causing it to shut off until that's eventually blown out?
     

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