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In 2008, the EPA began including the effects of air conditioner use in its fuel economy ratings.
Since that time, manufacturers have been making changes to improve the efficiency of their air conditioning systems.
One way to improve the efficiency of an air conditioner is by maximizing the use of recirculated air. If it's 72°F in the cabin, it's much less efficient to remove heat and moisture from 75°F or 100°F outside air and continuously push it through the cabin than it is to remove just enough heat from the cabin air to maintain 72°F.
In full auto mode, the system will select the most efficient way to heat or cool the cabin - even if that means continuously recirculating the odor of flatulence, gym socks, or petrified french fries under the seat.
The 2018 Accord I traded for my 2019 RDX worked the same way - I never saw it automatically select outside air, but the outdoor temperature never fell below 68°F during the four months I owned it. My '17 Ridgeline and '16 CR-V would automatically recirculate only until the cabin was near setpoint. Previous vehicles going back to my '99 Regal would recirculate only when the interior was on fire and prioritized fresh air. As one who trades often and drives a lot of difference vehicles, I've noted a trend towards newer models using recirculation mode more often.
It feels like this has been settled, but I had my AC set to auto yesterday. It cooled the cabin. When the temperature reached the deisred point, the Circulation light did turn off.
It feels like this has been settled, but I had my AC set to auto yesterday. It cooled the cabin. When the temperature reached the deisred point, the Circulation light did turn off.
Thank you for the pic. Yours is working properly so there is hope that many of us will get a fix in a system upgrade. May I ask when you took delivery of your RDX and what model it is (base, tech or advance)?
In 2008, the EPA began including the effects of air conditioner use in its fuel economy ratings.
Since that time, manufacturers have been making changes to improve the efficiency of their air conditioning systems.
One way to improve the efficiency of an air conditioner is by maximizing the use of recirculated air. If it's 72°F in the cabin, it's much less efficient to remove heat and moisture from 75°F or 100°F outside air and continuously push it through the cabin than it is to remove just enough heat from the cabin air to maintain 72°F.
In full auto mode, the system will select the most efficient way to heat or cool the cabin - even if that means continuously recirculating the odor of flatulence, gym socks, or petrified french fries under the seat.
The 2018 Accord I traded for my 2019 RDX worked the same way - I never saw it automatically select outside air, but the outdoor temperature never fell below 68°F during the four months I owned it. My '17 Ridgeline and '16 CR-V would automatically recirculate only until the cabin was near setpoint. Previous vehicles going back to my '99 Regal would recirculate only when the interior was on fire and prioritized fresh air. As one who trades often and drives a lot of difference vehicles, I've noted a trend towards newer models using recirculation mode more often.
A cold front came through last night lowering the temperature to about 55F. I noticed when driving today that the auto light was on and the re-circulation light was off, meaning to me that the outside temperature was cool enough for the auto function to take in outside air. In the warmer weather the auto function seemed to always force the re-circulation light to come on and favor inside cabin air. I think a few others in this thread I opened awhile back have confirmed this, so I think we have a better understanding how this control is designed to work. Thanks all for comments and inputs.
Same thing here. When the outdoor temperature dropped to about 68 degrees the "Auto" function switched from recirculate to fresh air. This is what should happen at all outdoor temperatures when the selected cabin temperature is reached. It is clearly just one more software error. Maybe Acura will get off their butts soon and fix some of these problems that we are having.
Same thing here. When the outdoor temperature dropped to about 68 degrees the "Auto" function switched from recirculate to fresh air. This is what should happen at all outdoor temperatures when the selected cabin temperature is reached. It is clearly just one more software error. Maybe Acura will get off their butts soon and fix some of these problems that we are having.
This is not a software error. It is intentional behavior!
Let's say it's 85°F outside and you have the system set to 72°F. If the system switched to outside air once the cabin reached 72°F, the system would need to cool and dehumidify the 85°F outside air. This is HORRIBLY inefficient! It's MUCH more efficient to remove the small amount of heat and humidity from the air inside the cabin that has already been cooled and dehumidified for the most part.
If anything, vehicles that switch to outside air once the setpoint is reached on a 100°F day are the ones with the "software error"!
Imagine how high your electric bill would be if the air conditioner in your home pulled in hot air from the outside instead of recirculating the inside air!
Sorry, you are wrong. I will pay for fresh air and it IS a software issue. Acura went for government mileage credits at the expense of providing us with stale cabin air. The system should switch to fresh air and you can turn it off manually if you want to. I suspect that most of us would rather not breathe elevated CO2 levels and air contaminated with plasticizers as the "normal, to each his own. They could have pleased everyone by allowing us to set the preferred mode but then they wouldn't get the government mileage credits. Same thing goes for the ridiculous engine stop mode which cannot be defeated without pushing a button each time you start the car.
Sorry, you are wrong. I will pay for fresh air and it IS a software issue. Acura went for government mileage credits at the expense of providing us with stale cabin air. The system should switch to fresh air and you can turn it off manually if you want to. I suspect that most of us would rather not breathe elevated CO2 levels and air contaminated with plasticizers as the "normal, to each his own. They could have pleased everyone by allowing us to set the preferred mode but then they wouldn't get the government mileage credits. Same thing goes for the ridiculous engine stop mode which cannot be defeated without pushing a button each time you start the car.
Your preference for fresh air or opinion of idle stop does not change the laws of physics.
Acura allows you to choose recirculated or outside air at the press of a button. The system defaults to the most efficient method. If you prefer to use more fuel in exchange for more outside air, feel free to press that button! Unless you have an HRV or ERV on the air conditioner in your home, you don't have the option to choose outside or recirculated air - it's always recirculated.
Acura allows you to disable idle stop by pressing a button each time you start the vehicle. Sure, that's not as convenient as a persistent setting, but be thankful you don't own a GM with idle stop that cannot be disabled!
Those preservatives and flavor enhancers in the lunch you ate today, the chemicals in your flooring and paint, and the bugs that the restaurant employee didn't wash off their hands after using the bathroom will kill you faster than anything being recirculated inside your vehicle.
I'll be happy to discuss the thermodynamic principles of automotive air conditioning systems in greater detail after you've received your engineering degree.
Your preference for fresh air or opinion of idle stop does not change the laws of physics.
Acura allows you to choose recirculated or outside air at the press of a button. The system defaults to the most efficient method. If you prefer to use more fuel in exchange for more outside air, feel free to press that button! Unless you have an HRV or ERV on the air conditioner in your home, you don't have the option to choose outside or recirculated air - it's always recirculated.
Acura allows you to disable idle stop by pressing a button each time you start the vehicle. Sure, that's not as convenient as a persistent setting, but be thankful you don't own a GM with idle stop that cannot be disabled!
Those preservatives and flavor enhancers in the lunch you ate today, the chemicals in your flooring and paint, and the bugs that the restaurant employee didn't wash off their hands after using the bathroom will kill you faster than anything being recirculated inside your vehicle.
I'll be happy to discuss the thermodynamic principles of automotive air conditioning systems in greater detail after you've received your engineering degree.
Thanks for assuming that I don't know what I'm talking about. To use your analogies I guess that if a little bit of pollution is bad then more of it is better? Is that why in homes that are highly efficient they install fresh air heat exchangers? If the RDX cabin is tight then excess C02 makes you drowsey in addition to the unhealthy chemicals and the exhales from your passengers. If the cabin isn't tight (which it is) then you are cooling some degree of outside air anyway. I seriously doubt that you could measure a change of milage with the A/C on recirculate vs fresh air, try it and let me know.
BTW, I have a physics degree which includes thermo dynamics and I worked as an engineer at the Carrier AC Company large centrifugal division. A couple of my jobs are cooling the Sears Towers and the Dallas Ft. Worth Airport. Enough of the personal attacks.
Thanks for assuming that I don't know what I'm talking about. To use your analogies I guess that if a little bit of pollution is bad then more of it is better? Is that why in homes that are highly efficient they install fresh air heat exchangers? If the RDX cabin is tight then excess C02 makes you drowsey in addition to the unhealthy chemicals and the exhales from your passengers. If the cabin isn't tight (which it is) then you are cooling some degree of outside air anyway. I seriously doubt that you could measure a change of milage with the A/C on recirculate vs fresh air, try it and let me know.
BTW, I have a physics degree which includes thermo dynamics and I worked as an engineer at the Carrier AC Company large centrifugal division. A couple of my jobs are cooling the Sears Towers and the Dallas Ft. Worth Airport. Enough of the personal attacks.
Then you should fully understand why automakers have been revising climate control logic in recent years to utilize recirculated air for longer periods of time under a wider range of conditions.
I'm an industrial heating and automation engineer. I write PLC software with safety, efficiency, reliability, and simplicity in mind. The equipment I design is used by many industries including automotive suppliers such as Magna, Bosch, TI Automotive, Bodine, Purolator, Detroit Diesel, AGC Automotive, and Cummins. We also supply a few other recognizable brands such as General Electric, Pratt & Whitney, and...wait for it...Carrier/Carlyle! I'm also an EPA-certified MVAC technician and the hair on my neck stands on end when people refer to R-1234yf as "Freon" or "coolant".
We can throw around credentials all day long, but neither of us can change the laws of physics. You're also assuming that there is zero flow-through ventilation when the "recirculate" light is illuminated without considering partial recirculation modes or that the recirculation mode door is operated with an actuator that is capable of varying the amount of recirculated air. Automobiles are not gas-tight.
Then you should fully understand why automakers have been revising climate control logic in recent years to utilize recirculated air for longer periods of time under a wider range of conditions.
I'm an industrial heating and automation engineer. I write PLC software with safety, efficiency, reliability, and simplicity in mind. The equipment I design is used by many industries including automotive suppliers such as Magna, Bosch, TI Automotive, Bodine, Purolator, Detroit Diesel, AGC Automotive, and Cummins. We also supply a few other recognizable brands such as General Electric, Pratt & Whitney, and...wait for it...Carrier/Carlyle! I'm also an EPA-certified MVAC technician and the hair on my neck stands on end when people refer to R-1234yf as "Freon" or "coolant".
We can throw around credentials all day long, but neither of us can change the laws of physics. You're also assuming that there is zero flow-through ventilation when the "recirculate" light is illuminated without considering partial recirculation modes or that the recirculation mode door is operated with an actuator that is capable of varying the amount of recirculated air. Automobiles are not gas-tight.
Logically when we select (or auto mode selects) "recirculate" there should be no partial mix with outside air. When driving past odorous or smoke filled areas I don't want outside air in the cabin. If there is a modulated fresh air damper then it should only function in "fresh air" mode. That's just my opinion. It would help us to understand what truly happens if Acura would provide a more thorough description of this function.
Although I center my reply to the 2019 MDX which I leased in June 2019, i read this thread with interest because i noticed the same behavior in the MDX. All the other cars that I have had with Auto AC, always automatically recirculated the air in the cabin for fast cooldown. Which as an aside you should crack open all windows for a short distance to force the hot cabin air out. After cabin ix cooled to the desired temp, the recirculation system shkuld then introduce outside air or fresh air as they call it. Of course, the outside temp and humidity makes that feature vary in its operation. The posts here have enlightened this old car owner , at 68 I guess you never stop learning. Fuel efficiency is all the car makers care about due to MPG ratings they need to meet. If they can tweak 1 more tenth of a MPG from this ac manner, across their entire fleet , they will do it. The same with auto On and Off feature, it increases MPG of tge car , using that feature as designed which is all the time. Luckiky, Acura included a turn off button. But i have begun to get hsed to it. Betcha all car makers who employ this to save gas feel the same way.
Although I center my reply to the 2019 MDX which I leased in June 2019, i read this thread with interest because i noticed the same behavior in the MDX. All the other cars that I have had with Auto AC, always automatically recirculated the air in the cabin for fast cooldown. Which as an aside you should crack open all windows for a short distance to force the hot cabin air out. After cabin ix cooled to the desired temp, the recirculation system shkuld then introduce outside air or fresh air as they call it. Of course, the outside temp and humidity makes that feature vary in its operation. The posts here have enlightened this old car owner , at 68 I guess you never stop learning. Fuel efficiency is all the car makers care about due to MPG ratings they need to meet. If they can tweak 1 more tenth of a MPG from this ac manner, across their entire fleet , they will do it. The same with auto On and Off feature, it increases MPG of tge car , using that feature as designed which is all the time. Luckiky, Acura included a turn off button. But i have begun to get hsed to it. Betcha all car makers who employ this to save gas feel the same way.
After having the 2019 RDX Advance for a year, it has been through all seasons and where I live the temp is almost always between 10F and 90F. The cabin air circulation light is on in the summer months the vast majority of the time when in auto mode and off in the winter when in auto mode. That tells me that it is able to heat the cabin effectively using cold outside air but not cool the cabin effectively when using warm, humid outside air. It all makes sense. But I do go out of auto mode and control the air circulation manually sometimes to pull in outside air or to block outside air when noxious exhaust fumes seem to be around.
09-20-2018, 03:56 PM
