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Rx400H A/c "re-Circulate" Button Annoyance; Smog Sensor?


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Hey guys,

I've had just about all i can take of the "re-circulate" setting changing on it's own for the A/C; switching from "inside air" to "outside air" without any input. I need some help!

Here in RI, winter mornings are frigid and everyone keeps their fireplaces on, stinking up the roadways with the smell of smoke. When i start driving when the car is cool, i like to keep the "re-circulate" button ON for the air conditioning so it warms up quicker (as it takes longer to warm up new cold outside air vs interior air) until the cabin temp is satisfactory. Well, at the SAME distance away from my house (and after about 3 minutes of driving) the "re-circulation" setting automatically changes to "outside air", with the green light going out automatically. It just so happens that this same "location" away from my house is ALWAYS smokey and the smell drives me NUTS. And by the time i catch the "setting change" it's usually too late, and i've gotta smell the smoke for a while.

Here's the button which controls the setting.

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WHY DOES IT DO THIS? I "think" there's something called a "smog sensor" that's supposed to detect the outside air quality in order to adjust between inside and outside air; but apparently it's malfunctioning! If i set the A/C to "re-circulate", i expect it to remain on "re-circulate" FOREVER, until i tell it to do otherwise.

I looked in the manual but of course there's no mention of this feature. Does anyone know how to turn this stupid feature off? It's always done this, for as long as i can remember- and it always changes at the same location whenever the outside temp is low. I don't think it does this as much when it's warmer out...

Is anyone else experiencing this problem? Thanks for any input!

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You need to have the dealer turn off the "auto-recirculate" under "personalized settings." If you had this done before the 5K service, they would have done it for free. They will probably charge you to do it now.

I HATE the way this function is programmed at the factory. I like to have control over this and don't want the vehicle's HVAC system to decide when it should be on recirc.

We had the same issue with our Camry hybrid. When I brought it up with that service writer, he acted like they never heard of it before. The service manager had to "open up a case with Toyota" to figure out what to do, and this is a GOOD service dept. Apparently very few people think like you and I do on this. I'll tell you this; I will make sure this is done BEFORE taking delivery of my next Toyota.

I'm also "old school" with the A/C compressor, ALWAYS turning it off a half mile or so before parking the vehicle if it's been on. I run with it off whenever possible. One drag about the third generation is getting to that "button" in the menu. I guess once you get used to accessing the screen functions with Remote Touch it's OK, but what could be easier than the touchscreen in the '08?

Good luck and hopefully your Lexus service dept. will change the setting for free.

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Turning off the "auto-recirculate" isn't the problem. The "auto-recirculate" is the function that automatically puts the system in "re-circulate" mode when you first start the engine and the cabin temperature is eleviated...typical summertime day.

Even in a "normal" car (non-NipponDenso, Denso US) climate control design, it can be hazardous to use re-circulate mode for an extended period on a coolish, or cold, day.

NipponDenso designed systems have a rather serious design flaw pertaining to this very same operational area. Those designs are even more prone to suddenly turn hazardous, quickly fog over the interior windshield surface, on a coolish or cold day.

The base problem is that in recirculate mode any moisture somehow trapped within the cabin, wet coat, wet folded umbrella, might raise the cabin Rh high enough that windshield fogging results.

To help alleviate that possibility ALL modern day vehicles will remove re-circulate mode within about 2 minutes in order to FLUSH the cabin of stale/humid atmosphere.

A note of CAUTION...!

Should you by chance find yourself with a windshield that begins to fog over while underway, or even actually suddenly FULLY fogs over, simply switching the system to defrost/defog/demist will not suffice.

You MUST also simultaneously turn the HEAT up to MAXIMUM in order to most quickly remove the condensation and/or reverse the trend.

Because of the flaw in the design it is best to disable the A/C throughout the period wherein cooling is not needed/desired. Lexus has a C-best option, 2 actually, that will allow you to disable the A/C indefinitely, even in defog mode, until you wish to use it for actual cooling.

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To help alleviate that possibility ALL modern day vehicles will remove re-circulate mode within about 2 minutes in order to FLUSH the cabin of stale/humid atmosphere.

My wife's 2010 Equinox can be put in recirc and it will stay there indefinitely for the rest of that ignition cycle. However, it will automatically engage the A/C compressor when recirc is selected. Her 2006 Impala was the same.

On my RX400h, if I select MAX cool, the system goes into recirc and stays there. It does not revert to fresh anytime as long as MAX cool is selected.

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thanks for the help guys,

lemon- I actually never use the "AUTO" feature of the A/C... I always adjust everything myself manually, with the dual climate control ON. The last time i hit the AUTO button was by accident a few months ago...

And i keep the "A/C" button off during winter months and turn it back on once i need it for cooling (usually in April). I'm a reptile; i love heat. The lowest i ever set my A/C to in the winter is "maybe" 73 if the sun's out... Usually it's between 79 and MAX HEAT. I'm not even kidding!

This stupid thing did the automatic switch to "outside air" again tonight when i had it set to "inside air". About 99.5% of the time the "inside air" light stays on ON; and when i turn the car off, it's still ON, and when i turn the car on the next day it's still in "inside air" mode how i like it. The ONLY time it switches to "outside air" is about 3 minutes after the car's started when it's cool out... OR if i manually switch it to get rid of fog on the window by turning the defrosters on for a second. Once i turn defrosters off, the "inside air" light comes back on how i like it.

I've always disliked the A/C system on this vehicle. I LOVED the way the Rx300 worked; it did EXACTLY what i told it, even if it fogged up the entire car. Over the years i've gotten VERY good at adjusting the "inside" vs "outside" controls so the fog doesn't form while still giving me NO outside smells. And i'd like to do this with the 400h but it "thinks" it's smarter than me. HA.

Bobbass- i'll have to ask my dealer about the personalized settings for this feature... i hope they don't charge me for turning off this stupid thing- i never asked for it!

I honestly wish the 400h had mechanical valve controls on the dash instead of these stupid solid state "switches" that make changes on their own. First they made the gas and brake pedals "drive by wire" and now the A/C? I mean come on, talk about making things difficult... I don't like having to constantly say, "Did you see what the car just did?" every time i drive the thing and switches start going off on their own... FREAKY.

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Cduluk, can you try this next time and see what happens...

Hit the AUTO button first, then adjust everything - fan, temp, mode etc. (you'll have to turn AC off manually because AUTO turns it on) . If the recirc is on, turn it off then back on..if it's off, just turn it on. My reasoning is this...when you hit AUTO, the system does everything on it's own, however each setting you change yourself after hitting AUTO, then falls under manual control. I'm thinking if you hit AUTO then adjust everything yourself, the system will be truly in manual mode. Just a thought. I'm going to try in my vehicle what you do and see what happens...so turn fan on, select mode, select temp, select recirc, no AC?

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Tex,

I had to laugh when I saw your comment! Another high-tech feature some vehicles have that can be disconcerting for some is active-handling. Some vehicles do not allow the driver to turn it off.

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On the RX450h, I can turn the auto recir on and off in the software. If I turn it on, it will act like what the OP said, if I shut it off, the recire will stay where I set it to unless I turn on the front defroster. I think the RX400h doesnt have that option, only the dealer can turn it off.

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On the RX450h, I can turn the auto recir on and off in the software. If I turn it on, it will act like what the OP said, if I shut it off, the recire will stay where I set it to unless I turn on the front defroster. I think the RX400h doesnt have that option, only the dealer can turn it off.

The industry thinking, WRONG thinking, is that as long as the A/C is operational then it will have enough dehumidification capability to keep the cabin Rh within "safe" bounds insofar as windshield fogging is concerned.

The problem often results shortly after the A/C compressor is turned off, disabled for some reason and now the mositure previously condensed onto the evaporator vane/fin area will be released into the cabin.

The A/C compressor is disabled with the OAT below ~35F, or if you drive into such an area.

Other than the above condition unless you have the dealer set the c-best option otherwise the A/C will ALWAYS operate, often without an indication, in deforst/defog/demist mode.

So, yes, with many modern day cliamte control systems as long as the A/C is operational the system will remain in the selected, recirculate, mode. But beware of/if the compressor should be shut down for ANY reason, driving into a colder area, for instance.

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cduluk, I went out today and drove for about 1/2 hour. Here's what I did...started car, pushed climate button, turned fan on 2nd speed, set temp at 24 celsius, turned on recirc, made sure A/C was off Drove for 30 mins. Systems stayed in recirc for the entire drive. Outside temp was 5 celsius.

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My RX was in today for the pulley recall (turns out I needed a replacement). I had an ES350 (I think that's what it's called..lol) for a loaner. Sure enough, it wouldn't stay in recirc for any decent amount of time (I was driving so I didn't time it). One thing it did have for the recirc button was ON, OFF and AUTO. I have no idea why they have AUTO when the damn thing does whatever it wants anyway...lol.

I have no idea why my RX stays in RECIRC (except mine is a 2006 and Cduluk is a 2008 - software program changes??)

On another note, isn't kind of sad that the majority of the motoring public are too clueless to know to switch from fresh to recirc if the windows start fogging up. Why else would car manufacturers need to program the recirc to switch off automatically...

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So, yes, with many modern day cliamte control systems as long as the A/C is operational the system will remain in the selected, recirculate, mode. But beware of/if the compressor should be shut down for ANY reason, driving into a colder area, for instance.

The new RX also have a auto AC on and off selection. One of the best thing Lexus did with the new models is that they brought a lot of the customized setting onto the screen so the one doesnt have to go to the dealer to chnage them.

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One must remember the the Hybrid Batterys work best between 70 and 80 degrees. So using the vehicle A/C helps regulates the battery temp that is why the vehicle has vents inside and not outside as the first Prius did.

There is an air intake vent under

the rear seats to cooling the hybrid

battery (traction battery). If the

vent becomes blocked, the hybrid

battery may overheat, leading to a

reduction in hybrid battery output

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Lemon, it worked! However it would require me to do this every time I start the car. If upon startup I hit AUTO, then turn it off (and of course re-adjust all settings) it doesn't switch to "outside" air as quickly.

And I agree, I don't understand the purpose of the AUTO feature, as even with AUTO off, it still does what it wants! I'll give this another few days but this car is dealer bound! I'm hoping the dealer can get rid of this feature :(

I'm wondering if your 06 isn't doing it because of your climate or if there's a difference between the computers between 06 and 08. Or it could be there is indeed a fault with mine, maybe a blown out sensor? I swear it switches to outside air the second smoke is around!

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My RX was in today for the pulley recall (turns out I needed a replacement). I had an ES350 (I think that's what it's called..lol) for a loaner. Sure enough, it wouldn't stay in recirc for any decent amount of time (I was driving so I didn't time it). One thing it did have for the recirc button was ON, OFF and AUTO. I have no idea why they have AUTO when the damn thing does whatever it wants anyway...lol.

I have no idea why my RX stays in RECIRC (except mine is a 2006 and Cduluk is a 2008 - software program changes??)

On another note, isn't kind of sad that the majority of the motoring public are too clueless to know to switch

"...from fresh to recirc if the windows start fogging up..."

Why else would car manufacturers need to program the recirc to switch off automatically...

Was that a typo or was backwards intentionally...?

Don't ALL modern day systems switch AUTOMATICALLY to FRESH when you activate defrost/defog/demist, or even partial windshield flow...?

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Lemon, it worked! However it would require me to do this every time I start the car. If upon startup I hit AUTO, then turn it off (and of course re-adjust all settings) it doesn't switch to "outside" air as quickly.

And I agree, I don't understand the purpose of the AUTO feature, as even with AUTO off, it still does what it wants! I'll give this another few days but this car is dealer bound! I'm hoping the dealer can get rid of this feature :(

I'm wondering if your 06 isn't doing it because of your climate or if there's a difference between the computers between 06 and 08. Or it could be there is indeed a fault with mine, maybe a blown out sensor? I swear it switches to outside air the second smoke is around!

For whatever reason the dealers are reluctant to show you the FULL c-best listing. The want you want to see will have the capability of disabling the A/C indefinitely, throughout multiple engien starts, until you depress the A/C PB to re-enable it. There is a second one that will unlink the A/C from automatically operating, with an indicator, in defrost/defog/demist mode, or even partial windshield airflow mode.

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That's the thing though, i don't care about the "A/C" being activated- the only problem i am having is with the "inside" vs "outside" air settings changing on their own without me hitting ANY buttons. As far as the "A/C" feature goes, if i press it ON it stays ON until i press it OFF. I'm not sure what it does when i turn on the defrosters, but whatever it's doing to the "A/C" is fine with me. The only thing i do notice when i turn on defrosters, is that it turns "outside air" ON until i turn the defrosters OFF- this i like however!'

My issue is only with the fact that it toggles between "inside" and "outside" air at random times without me touching any buttons. I don't have the system set to "AUTO", i don't have the defrosters on; yet it still changes on its own...

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My RX was in today for the pulley recall (turns out I needed a replacement). I had an ES350 (I think that's what it's called..lol) for a loaner. Sure enough, it wouldn't stay in recirc for any decent amount of time (I was driving so I didn't time it). One thing it did have for the recirc button was ON, OFF and AUTO. I have no idea why they have AUTO when the damn thing does whatever it wants anyway...lol.

I have no idea why my RX stays in RECIRC (except mine is a 2006 and Cduluk is a 2008 - software program changes??)

On another note, isn't kind of sad that the majority of the motoring public are too clueless to know to switch

"...from fresh to recirc if the windows start fogging up..."

Why else would car manufacturers need to program the recirc to switch off automatically...

Was that a typo or was backwards intentionally...?

Don't ALL modern day systems switch AUTOMATICALLY to FRESH when you activate defrost/defog/demist, or even partial windshield flow...?

Ack...lol. Backwards. I mean too clueless to switch from RECIRC to FRESH if the windows start to fog up. Yes, that's my point. The car does it automatically now because most people don't think to do it themselves. Every winter I see older Toyota Corollas and Honda Civics with all the windows fogged up and I can almost guarantee that they are driving around with RECIRC on.

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And I agree, I don't understand the purpose of the AUTO feature, as even with AUTO off, it still does what it wants! I'll give this another few days but this car is dealer bound! I'm hoping the dealer can get rid of this feature :(

I flipped therough the owner's manual for the 2011 ES350 loaner I had and the AUTO position for the fresh/recirc button is for bad smell/exhaust. I suppose it switches automatically to recirc if it senses bad things(exhaust? carbon monxide? hydrocarbons? cow manure???) We don't have that feature/sensor in the 400h.

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And I agree, I don't understand the purpose of the AUTO feature, as even with AUTO off, it still does what it wants! I'll give this another few days but this car is dealer bound! I'm hoping the dealer can get rid of this feature :(

I flipped therough the owner's manual for the 2011 ES350 loaner I had and the AUTO position for the fresh/recirc button is for bad smell/exhaust. I suppose it switches automatically to recirc if it senses bad things(exhaust? carbon monxide? hydrocarbons? cow manure???) We don't have that feature/sensor in the 400h.

So there's a separate "AUTO" button for the "inside/outside" air system on the new ES?? I thought we were talking about the "AUTO" button on the dash face that... well, is supposed to regulate fan speed and what not based on what temps we select (which i don't even think works).

And i thought our 400h was supposed to be able to detect bad smells too? I know mine doesn't as it always seems to take outside air when the outside air smells! It could just be broken though...

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Yes, there is the AUTO button for the climate control, then there is one button for fresh air/recir. Push once for fresh, push again for recirc, push again for AUTO (which is the smog sensor setting). I'm pretty sure we don't have any sort of smog sensor linked to the RECIRC on the last generation RX.

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Yes, there is the AUTO button for the climate control, then there is one button for fresh air/recir. Push once for fresh, push again for recirc, push again for AUTO (which is the smog sensor setting). I'm pretty sure we don't have any sort of smog sensor linked to the RECIRC on the last generation RX.

Damn... so the only reason mine seems to change between "inside" air and "outside" air is by a clock? Either that or it detects moisture... which i doubt!

Oh yeah, this feature is getting the boot. i'm on vaca this week until the 19th but when i get back it's going to the dealer. I need a lot of things looked at. I still have that "farting" noise when i brake, my rear-view mirror compass keeps "blinking" (there's gotta be a lose wire up there) and there's a squeak in the back seats i can't get rid of! This thing is really showing it's age at almost 80k miles :( Warranty ends this June so i've gotta get these things fixed ASAP. I'll see about all these recalls too...

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