Comparing with my 2004 TL, on the TL when I turned the AUTO button on the climate control system and it was very hot in the interior from sitting in the sun, the cabin recirculation was automatically engaged so that the interior could cool faster. Once cooled sufficiently, the light for the cabin recirculation button would go off and external air would flow. AUTO remained on for the whole time. That is how I think the RDX should work too.

But the 2019 RDX behaves differently. No matter the interior temperature of the car (even after sitting in the garage overnight), if AUTO is on, cabin re-circulation is on. When I depress the cabin re-circulation button to go to outside air, the AUTO function goes off. I prefer to run with external airflow most of the time especially when the new car smell is fairly strong. It looks like I can’t run the AUTO setting if I want external air. I would doubt that this is the design.

Can anyone check this out on their 2019 RDX and post a reply? I want to see if my specific vehicle has a malfunction or if others behave this way too before I schedule a service visit. Thanks.

 

I should add that on the RDX when I push the AUTO button, the cabin re-circulation light always goes on, so there is always a relationship with AUTO on, cabin re-circulation on and with AUTO off, cabin re-circulation off.

 

I have this same feature in my Buick and it does bother me at times. Don't know that there is a way to disable it. Just how they make climate control now probably...

 

I hadn't noticed before but, I've tested mine and in running errands today for a couple of hours on Auto, which is how I run year-round, the Recirc button stayed lit the whole time.
In my TLX, Recirc went out as soon as the set temperature was reached.

Like you, I'm not too happy with this.

 

catbert - Thanks for checking this out. I appreciate it. I guess this is a design issue and not a break-fix issue in terms of my specific vehicle since yours is behaving the same. I am going to contact my dealer and after I bark a bit, I am going to ask exactly what I lose in climate control if I set a temperature, set external air flow, and have auto off. Will it still provide the desired temperature control and fan speed? I need the external air because the new car smell can be a bit overbearing with just recycled internal air.

 

After thinking about this, In my mind this AUTO-recirc issue is a software bug in the climate controller that slipped through testing and out the door so it is a break-fix issue. I can't imagine the rationale for changing its behavior as a design change. Calls and emails to both the service department and sales contact at the dealer might get the engineers to look into it. I may end up taking it in for service anyway on this. Even though it is a small thing given the grandeur of the vehicle I don't want to live with this for several years.

 

Please let us know what the service manager has to say.

Robot voice: "It is functioning normally per manufacturer specification".

 

 

While it looks like Auto is disabled, the manual says that even when you manual select a circulation mode, the system is still automatically controlling the other settings.

"If any buttons are pressed while using the climate
control system in auto, the function of the button
that was pressed will take priority.
The AUTO indicator will go off, but functions
unrelated to the button that was pressed will be
controlled automatically."

Page 230 from the digital manual BTJB1818OM.PDF

 

Interpretation of accord1999 post taken from the manual: It looks like for most if not all situations that the default circulation setting with AUTO on is inside cabin air and you have to push the recirc button to switch to outside air turning off the AUTO indicator. So it is a design change relative to at least some earlier Acura models.

 

 

In summary it looks like for most conditions you set the temperature that suits you, depress the AUTO button which also invokes internal cabin circulation, and if you wish external circulation, you depress the RE-CIRCULATION button turning that display light off and the AUTO display light too. From the manual excerpt it looks like AUTO is truly invoked in this sequence even if its display light is off. Seems counter-intuitive to me to have a function invoked despite the fact that its indicator light is turned off, but I guess it is what it is and perhaps this thread helped in that understanding. Thanks all for you comments.

 

That isn't the way it works on my '16 Advance. The system stays in recirc until the set temperature has been reached and the fan has slowed down to one of it's 2 lowest speeds. Then the recirc light goes out. If you're not watching, you can tell. The air gets slightly more humid and the smell of the air coming out of the vents changes. This condition is almost never reached unless I've been on the highway with temperatures below 80° outside, so it stays in recirc about 98% of the time. I'd be surprised if this logic has changed.

 

Honda changed the programming for the A/C to offer blending in the recirc mode so you don't get the stale odor from recirc systems settings of the past. They are trying to save every drop of gas in the new vehicles by maximizing the recirc setting without the adverse effects of a 100% recirc system. Long thread on this on the Honda Ridgeline forum.

 

By coincidence my 2019 RDX - Advance is at the dealer for repair of another defect. In the eight weeks I have had the car the recirculate mode never changes unless I push the recirculate button to turn it off, whereupon the auto indicator also goes off. I took the occasion to bring up this very issue with the dealer and asked them to get a response directly from Acura. In my opinion if the A/C control is truly automatic then it should only use recirculate mode when it is required to rapidly cool or heat the car to the selected temperature. After reaching the set point then it should switch to fresh air. This is exactly the way the system works in the 2018 TLX loaner vehicle I am driving. Continuously breathing recirculated air is unhealthy and as CO2 levels increase it leads to drowseyness which is a safety issue. I will post the official response from Acura when I have it.

 

 

I've had vehicles in the past where an indicator (A/C, Recirc) meant the function was 'available' but not necessarily 'in use' at any given point in time. That's may be how both these work on the '19 RDX.

It may also be the 'recirc' mode is actually a blend of recirculated and fresh air depending on the needs of the system at a given point in time as some vehicles I've owned in the past functioned. Unfortunately the owner's manual doesn't allude to this at all.

Recirculation mode (indicator on): Recirculates air from the vehicle’s interior through
the system.
Fresh air mode (indicator off): Maintains outside ventilation. Keep the system in
fresh air mode in normal situations.

 

Thanks in advance for posting Acura's response to this. I am interested in it. Right now I am under the assumption that there is no sensor based control of interior vs. exterior air flow. It is strictly in the hands of the occupant by using that button.

 

 

Thanks for the info. I guess over time we will all understand this better as we use our new vehicles for a longer period of time under different conditions. The only time I ever manually used the re-circulation button to the internal air setting on previous cars was to keep foul smells out such as from a smoking exhaust pipe.

 

I apologize in advance if it appears like I am beating a dead horse on this, but I would like to propose a summary statement based on the posts thus far:

1. If the occupant has set the air re-circulation toggle so that its light is off, the airflow is from outside the vehicle (all the time?).
2. If the occupant has set the air re-circulation toggle so that its light is on, sensors determines the airflow mix between inside air and outside air based on temperature and humidity.
3. There is no setting that the occupant can select to guarantee (near) 100% inside air flow for a period of time say to eliminate noxious exhaust or other foul smells from entering the vehicle (unless of course the temperature sensor can sense air quality in addition to temperature and humidity which is doubtful). It is probably better to use #2 above to increase odds of at least some re-circulation thus reducing the outside odor in the vehicle.

Is this kind of where we are at? I plan to keep this vehicle for awhile so I would really like to understand this beyond what the online pdf spells out..

 

I think we need Acura to tell us how the air distribution works. In previous cars that I have owned, when you press the recirculate button the indicator turns on and cabin air is recirculated without a mix from the outside. With the new RDX I assume that when the recirculate indicator is on (which is 100% of the time in "auto" mode) that it is recirculating cabin air exclusively. I will clarify this at the dealer or perhaps someone who has already figured this out will respond.

 

 

Per the owner's manual (see post #17 above) 'recirc' on - only recirculated air, off - only outside air. Don't know that anyone has reliably shown otherwise yet.

 

 

Personally, my system never gets COLD... It gets cool, but never cold, so I have to run the settings on LO and AUTO almost all of the time and the cabin area never gets comfortable. The vehicle is in for service to see what is going on with this issue.

 

I certainly don't have that problem. With other vehicles I've usually had the temp set to 67-69 as a comfortable level. With my RDX anything lower than 70 gets uncomfortably cool.

I have noticed that at times when the A/C is on and it gets a bit too cool for the system's liking it will actually output a bit of warm air for a few seconds to bring the temperature up to where it's set and then return to normal A/C operation.

 

Same with mine! It's been in the upper 90's here when I get off work.. the AC get real cold, real fast. I have mine set at 70 and sometimes have to raise it up to 72

 

I have no problems with the cooling performance. Virtually every car I have ever driven, I set the air temperature maybe 5 degrees colder than what I set in my house to achieve the same level of comfort.. That seems to be the case with my 3G RDX.

 

I have the same issue; I am not pleased how this system works so far. My truck has a "MAX A/C" setting, which is recirculating all the time. This system will get cold.

 

I was given a 2018 RDX as a loaner while mine is in for service and it gets COLD, not cool.... Obviously there is an issue that needs to be addressed and I hope they find the problem

 

Test drove an Advance AWD and the car would not cool down during the drive. Was sweating the entire time with the system set to Auto/Lo. Salesperson shrugged it off.

 

There is clearly something wrong there. I have a 2016 RDX Advance and the A/C literally gets ice cold within seconds of turning it on.

 

My comment is that the AC in my 2019 does not seem to dehumidify. I've assumed it to be due to some sort of 'green' endeavor.
At 80° I need to set it at 69°, where as in the 2004 TSX (Japanese built) comfortable at 75° setting consistently.
If I have to set it to a cooler temperature, does it not just use more energy?

 

By the mere nature of having the AC on it acts as a dehumidifier.

 

OK, to clarify, it does not seem to dehumidify adequately.

 

A few years ago, around 2014, automakers started to switch the refrigerant from R134a to a newer more environmentally friendly R1234yf that is somewhat less efficient, but has lower Global Warming Potential. Similar to the switch from R12 to R134a auto AC systems will need to be redesigned to maximize the cooling properties of the new refrigerant. I remember the first car I had with R134a never seemed to cool as well as my older car with R12. Supposedly, R1234yf is compatible enough to be a drop-in replacement for r134a, but I've read where some R1234yf systems have a an inline heat exchanger to sub-cool the liquid refrigerant coming out of the compressor to improve performance.

 

At least the RDX, unlike my 2015 TLX, AC condensate does not stay trapped on the evaporator and then starts to become mildewed and make the car smell like dirty socks when you start the AC for the first time after the car has sat over night. That alone was almost reason enough to get ride of the TLX, but don't get started on what Acura did wrong with that car.

 

Regarding the recirc vs outside air. Once I was driving a 3 hr road trip at night. At the beginning of the trip, when I put it in auto, the system went into recirc mode. At that point the outside temp was slightly higher than the cabin temp setting. And sometime during the trip (maybe 1 to 1.5 hr later), I notice the HVAC system turn off recirc and was using outside air. At that point the outside temp was 6 degree F lower than the cabin temp setting. So it will switch, but not sure until what conditions.

 

Since the vehicle has only been around in the summertime, that could explain why engaging the auto setting always seems to mean cabin air circulation. When the cooler fall weather arrives, then we should experience external air (re-circulation light goes off) coming into the cabin when the auto setting has been engaged.