HVAC always seems to run on fresh air mode

tomp · Jul 14, 2015

Hi all,
I've noticed that my HVAC has seemed to always be in fresh air mode lately. I am trying to test it out more and am wondering if there are scenarios when the HVAC would be expected to be on recirc. Over the past couple weeks, I have not yet noticed the HVAC in recirculate mode when it is on Auto. It seems like it would be more efficient to use recirc mode more. I have noticed this trend whether on range mode or normal.

This thread indicates that the HVAC tends to default back to fresh air when put on recirc, and that it will switch over between the two modes every few minutes. My experience has been it always seems to run on recirc.

So, is there a scenario where HVAC should end up on recirculate mode? What have you all experienced?

mibaro2 · Jul 14, 2015

It always seems to be in fresh air mode if left on auto.
I need to manually switch it to recirculate.
You would think that if you put the A/C on, and temp as LO , that it would go to recirculate mode. But in my experience this doesn't happen.

JPP · Jul 14, 2015

Hmmm...FWIW my system seems to work in recirc initially then switches to fresh air. I assume that you have not accidentally switched into Custom Auto.

CHG-ON · Jul 14, 2015

I have not noticed it changing back and forth when in full auto. If I set it to recirc, which I usually do because ICEs just plain stink :cursing:, it does not ever change to fresh unless I choose it. It is quite obvious when it is in recirc because the fan noise and volume of air increase so much. So if it is changing back and forth in auto, it must also be adjusting the fan speed to keep the air volume about the same. I find it much more effective in recirc when cooling but it can get stuffy after a while.

KidDoc · Jul 15, 2015

I just keep my recirc on all the time and leave the rest on auto. On the display it lists my mode as "Custom auto" and it works SOOO much better.

sorka · Jul 15, 2015

I've also noticed this. Even when it's 100F outside, I have to switch to recirc to recirc manually. I just pretty much leave it on recirc now. Obviously a bug.

mibaro2 · Jul 15, 2015

JPP said:
Hmmm...FWIW my system seems to work in recirc initially then switches to fresh air. I assume that you have not accidentally switched into Custom Auto.

Didn't even know that Custom Auto existed. Didn't see any special indications on the hvac controls that it was in a special setting. I know have something to look up tonight.

GlmnAlyAirCar · Jul 15, 2015

From what I can tell, "auto" seems to find some intermediate ground between outside and recirc air. Driving home yesterday, I set it to recirc, and the fan went high and felt a lot of air moving. I set to outside air, and the fan stepped down with a similar reduction in noise and airflow. Then I went back to auto, and got behavior that was closer, but noticeably higher, than outside air.

mknox · Jul 15, 2015

mibaro2 said:
Didn't even know that Custom Auto existed. Didn't see any special indications on the hvac controls that it was in a special setting. I know have something to look up tonight.

If you pull up the controls, you can selectively put a/c, recirculate, mode and fan speed in either Auto or you can override one or more of them. Sometimes I don't want the a/c to come on, so I manually turn it off, manually turn re-circulate off, but leave Mode and Fan in Auto. When I exit, the main control will say "Custom Auto" as opposed to just "Auto"

- - - Updated - - -

JPP said:
Hmmm...FWIW my system seems to work in recirc initially then switches to fresh air. I assume that you have not accidentally switched into Custom Auto.

Mine works that way too. If it gets really hot, sometimes it might flip back into re-circulate for a while.

Personally, I prefer outside air over re-circulate, but if it's really hot, sometimes that taxes the system too much.

David99 · Jul 15, 2015

Mine definitely switched back and forth automatically. It just needs to be very hot for it to happen.

mibaro2 · Jul 16, 2015

mknox said:
If you pull up the controls, you can selectively put a/c, recirculate, mode and fan speed in either Auto or you can override one or more of them. Sometimes I don't want the a/c to come on, so I manually turn it off, manually turn re-circulate off, but leave Mode and Fan in Auto. When I exit, the main control will say "Custom Auto" as opposed to just "Auto"

- - - Updated - - -

Mine works that way too. If it gets really hot, sometimes it might flip back into re-circulate for a while.

Personally, I prefer outside air over re-circulate, but if it's really hot, sometimes that taxes the system too much.

Thanks. Seemed I had it on custom auto. So yesterday afternoon I set it to full auto, and it never went to recirculate. No matter how cold I put the temperature, it stayed on allowing fresh air in.
Since I usually adjust the fan speed or air input, I guess I will always be on Custom Auto.

mknox · Jul 16, 2015

mibaro2 said:
Thanks. Seemed I had it on custom auto. So yesterday afternoon I set it to full auto, and it never went to recirculate. No matter how cold I put the temperature, it stayed on allowing fresh air in.

That does seem odd. On Full Auto, mine will almost always start out on Recirculate, then flip over to outside air as the car cools down. The sound of this changeover is quite noticeable when it happens. Yesterday I didn't even have the a/c on since it has cooled down a bit. You and I are in roughly the same area. Maybe yesterday was cool enough that the car figured it didn't need Recirculate. Try it again when it gets hot.

I find that on Full Auto, the fan speed is often too low. I have my right scroll wheel set to Fan Speed by default. If I feel the fan is too slow, I can just flick it up a bit as I drive, then later press the scroll wheel to put it back in Auto.

GregoryWelch · Jul 18, 2015

It would be nice if the Recirculate setting could be learned and tied to GPS coordinates. I always set it to recirculate when I enter a carwash.

Barry · Jul 18, 2015

GregoryWelch said:
It would be nice if the Recirculate setting could be learned and tied to GPS coordinates. I always set it to recirculate when I enter a carwash.

Would also be useful when crossing Staten Island :smile:

mknox · Jul 20, 2015

GregoryWelch said:
It would be nice if the Recirculate setting could be learned and tied to GPS coordinates. I always set it to recirculate when I enter a carwash.

I just hit the main power button and shut the HVAC right off when I go through a wash. Done this for years to avoid sucking sudsy water into the system.

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HVAC always seems to run on fresh air mode

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