Nonestar

I notice in the 2024 Cayenne manual that the air recirculation, even if manually engaged, turns off after 5 minutes if the A/C turns off (which apparently happens in cold weather) when the engine is on/normal driving. Have any of you experienced this turning off of manual recirculation in cold weather? If so, what is the approximate outside low temperature that causes this behavior? (I assume recirculation stays on continuously if manually engaged if the A/C remains on in other environments.)

ThomasWShea

If you are talking about REST mode it runs for 20 mins. recirculating residual engine heat.

chassis

Engine on or engine off?

Nonestar

Engine on/normal driving; clarified in original post.

ThomasWShea

As far as the air recirculation, I recall in my prior audi, that turns off after some number of minutes. I read up on it at the time, and it was due to some fear that people would be in a low oxygen environment. I don't recall if it became regulated in the US, or if it was just something the manufacture decided to do (probably based on being sued or something).

clutchplate

I noticed this after a recent service and software update. My workaround is to push the auto/rest button and it then stays engaged. It also stays in memory when I restart the car. Not sure why they changed this but it only stays on for a few minutes doing it the old way.

chassis

Best practice with modern German cars is to use AUTO and set the desired temp. Let the system do its thing and the best possible (hopefully close to desired) results will be produced.

clutchplate

While that may be true in general, something in the most recent software update now prevents the re-circulation from staying on unless it's set to auto. It wasn't that way previously so it may be a glitch.

chassis

Deleted explanation of .1 tests. OP is talking about .2.

Sounds like .2 HVAC has less user controllability than .1.

ThomasWShea

so, the paper manual just doesn't go into detail, i noticed there are places in the paper manual that refer you to the digital manual, which I was ignoring assuming the paper manual was the most detailed. apparently that isn't the case. This is what the digital manual says:



Sounds like things are working as designed. You haven't stated your reason for wanting to force recirculation - frankly I am curious. if the goal was to just keep a specified temp, the system can do that perfectly fine on auto.

clutchplate

I'm a dunce and the above post is correct. Wife must have turned off the AC button causing the re-circulation to turn off in 5 minutes but after re engaging the recirc stays on.