I have noticed that when my climate control is set to "Auto" mode that it stays on Recirculation mode regardless if the car interior has cooled down.
It is summer time.. so I wonder if the Recirculation/Fresh Air mode based on ambient outdoor temperature?

 

Don't know where you are in Texas, but It's been hotter'n heck up here in DFW. As a result, your climate control system might well be keeping the system on recirculate to maintain the temp you've selected - especially if you've selected a pretty low temp like I do. As far as I know it's automatically controlled, so I wouldn't worry about it.

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I'm in Houston and keep mine on re-circ to keep the humidity down inside the car. This whole week, even with high quality tinting even on the windshield the A/C stays on full speed all the way home from work... about 15 minutes. It is that time of year.

 

I live in Houston, the Uptown area. It's been pretty hot lately. My car is garaged and I just noticed even in the morning it is in Recirculation mode and the cabin is not warm. I usually have it set to 73 degrees. So I wondered if the climate control Auto mode is based on outside temp and not inside temp? Or is it a combination of outside and inside temperatures that regulates how the Auto Climate Control works? I did look in that owner's manual and it was vague about this.

 

The programming probably varies by make but my past and current Lexus models also default to RECIRC for a long time in warm weather, also observed that on other cars I've had in the past. If you ruin in ECON it will stay on RECIRC, but I've see it go to FRESH on Sport mode (our normal mode) after a long while when temps are not that high.

 

The answer is yes. The car takes into account both the outside temp and the inside temp. On top of that, it adjusts for the direction you're traveling (like into the sun).

I've noticed my fan blows a LOT harder at the same set temperature than it did a month ago when it was cooler, so it's definitely adjusting based on the heat outside. And if I turn a corner from going west to going north, the fan immediately ramps down.

I'll watch mine today to see about the recirculate thing, but I'm pretty sure it knows what it's doing.

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I want my car on re-circ all the time. But if you turn off the climate control, it reverts to outside are. Another stupid programming flaw.

 

I drive in the sport mode and I haven't seen it change to Fresh yet. After reading the manual, I came away with the feeling that it wouldn't change in the Auto mode. However if you change it to Fresh, the light on the Auto switch goes out. I'm wondering if it's also taking humidity into account. While our mornings are cool in Florida, the humidity does stay high. I'll have to pay more attention this coming fall and winter when temps and humidity are more reasonable.

 

I never turn my climate control off, it stays on AUTO. I adjust the temp when needed by using the temp toggles. It stays in re-circ for me.

 

I actually just picked my 2015 TLX up after leaving it at the dealer for a few days so they could diagnose a damp, musty smell that is really noticeable when first turning the car on (with climate control left in AUTO mode).

Of course, they said they couldn't replicate it and despite me sitting in the car with them and smelling it, they still acted like I was nuts. Very frustrating considering the car only has 8,000 miles on it. I replaced the cabin air filter as well to no avail.

That being said, is there an optimal setting to keep the climate control on? I always used auto, but I'm sick of the dirty sock smell when I turn the car on. I see that AUTO mode can be turned off while still keeping the fan on AUTO - this allows re-circulation to be turned off, which might be helpful in reducing the smell, but what's the negative aspect to this setting? Will it still maintain my set temperature? If so, what's the point of AUTO mode then? Very strange if you ask me.

 

Auto will use the compressor (which condenses water out of the warm air; the water sits in the air plenums and can potentially mix with dust or dirt and get that musty smell). Without the compressor (Auto), however, you will not get cooling greater than the outside air temp. To try to resolve the musty smell, push the A/C-sync button, and select A/C off about half a mile from your last stop of the day in warm weather, and it should improve or resolve. I've done it since new--on all my current and previous cars, and no problems. In the winter, I don't use Auto--I just leave the A/C off. You'll note that when you select A/C off, the air flow graphic will switch from recirculated air to fresh as you finish your drive.

 

Mileage has nothing to do with it, driving conditions and usage is the key factor. Follow the tips provided by Jim, and research a product that is sprayed into the air intake to kill off the bacteria/algae.

It used to be recommended that you leave it in Auto or at least turn on the A/C a few times per month over winter to allow the system to engage and keep the compressor lubricated. I could not find anything in the Handbook about it, but it makes sense.

 

Honestly, I've never used the Auto feature in any of the three or four vehicles I've driven with it equipped...

In fact, I kind of hate it...

The only thing I like is having daul zone...

On the other hand, auto less unattractive knobs, looks cleaner...

But in my RDX, and a 2003 model Yukon I've driven a lot latly, I find the auto feature does some annoying things, i.e...

Fan blows so high at first my hair is all over the place (I guess it changes to a lower speed, but I haven't yet acquired the patience to wait it out)...

The Yukon chooses a default setting of defrost, why? I have to mash mode three or four times to get it to top vents... The RDX doesn't do this, thankfully...

In both vehicles, it automatically turns off recirculate, why again???

Honestly, it annoys the living sh*t out of me...

I just manually turn it to A/C ON, low or medium fan (at night, high it the day), and LOW temp setting, that's it... Oh, and the RDXs AC blows, the Yukon, and my old Camry (2001), are much colder... And it doesn't blow out cold when parked, nor do I stop sweating in the daytime, ever...

Pretty much everything other than a Honda/Acura and Kia/Hyundai have considerably closer A/C!!!

I've noticed the sub-par A/C in other Hondas, what gives???

 

"It used to be recommended that you leave it in Auto or at least turn on the A/C a few times per month over winter to allow the system to engage and keep the compressor lubricated."

Quandry--good point. I use the defog/defrost and need the compressor in the winter occasionally for window moisture control; that runs it, but I also try to remember to run it occasionally as you mention. I don't see that in any manuals anymore, probably the result of the increasing set it and forget it Auto on most cars. My one complaint is that there is not a more convenient "A/C on/off" button on the first tier of the display.

 

Thanks jim256, however when my car is in Auto climate mode, "AC" is never on (yet the air is still plenty cold - maybe it's just a programming error with the light?) and in fact, cannot be turned on if Auto mode is engaged. When I press the AC / Sync button and turn the AC on, Auto mode automatically turns off.

That being said, would you recommend I just turn re-circulation off a few minutes before the end of the drive?

 

When in Auto, that A/C display on the AC/Sync menu does not illuminate. If you turn A/C off, or on, you are taking control rather than Auto. If the plastic Auto button green light on the panel is lit, you'll have the compressor on unless it's about 35F or below. The best option to avoid musty smells is to push the A/C SYNC button near your journey end, hit A/C off, and the green Auto light will go off, and it will also automatically switch to Fresh air. 'Has worked for me on many cars.

 

Thanks for clarifying! I'll try that from now on and hope for the best. I appreciate it.