LX Auto Air Intake: Sensitivity Adjust

[Tinkerer]

Eureka!

Just noticed in the LX470 owners manual that one may adjust the HVAC Auto Air Intake system sensitivity, by special code entry pattern at the HVAC controls.

Press the HVAC Air Intake selector button & hold until the Auto button light flashes and the display indicates a number, then turn the temperature adjust dial to increase sensitivity (to 3) or decrease (to -3). Let go and leave it alone to revert to normal operation mode with your new sensitivity setting.

As this Auto Air Intake function is one of the things I really like about this vehicle (ability to detect & automatically block over-rich junkmobile exhaust and other toxic VOC fumes and keep them from entering the cabin), I am VERY happy to find this.

RTFM as they say.

Hope this is useful to someone else too.

 

[calamaridog]

Where is this control?

 

[Tinkerer]

Where is this control?

This works with the HVAC controls on the dash.

Air Intake selector button is the one on the lower left of the HVAC controls, that sets HVAC air source to fresh, recirc, or auto.

Auto button is the big one on the upper left of the HVAC controls, used to set the system to full auto as desired.

Temperature adjust dial is on the left side of the HVAC controls group.

Haven't confirmed the effectiveness of the sensitivity adjustment yet. I set it to "3" this morning, hoping that means "extra sensitive", but evidently I was lucky this morning and did not encounter any over-rich junkmobile exhaust.

 

[hoser]

Calamari, first it was the horns and now this. I bet you really wish you would've gotten an LX now.

 

[calamaridog]

Calamari, first it was the horns and now this. I bet you really wish you would've gotten an LX now.

No, but a I know just bought one and I like to sound smart

 

[Tinkerer]

Weird, after adjusting this a few times to the positive and negative, to observe results, it started acting freaky - erratically switching between fresh and recirc, more frequently than usual and for apparently no reason related to outside air quality.

So, warning to anyone wanting to try it. Not sure whether I've screwed it up, now, or whether this is some temporary "bug" in the control unit that has been brought out by this adjustment.

 

[Tinkerer]

After sitting overnight, the Auto Air Intake no longer acted freaky today (after freaking out last night upon sensitivity being adjusted several times).

Dunno if the +3 sensitivity setting is doing anything, though. Haven't encountered enough VOCs to tell yet.

FWIW

 

[tabraha]

Cool find. I love this feature too. Can't wait to crank it up to 3 and see if it helps pick up a little sooner. I wish it could detect roadkill skunk though.

 

[Tinkerer]

Update on sensitivity adjust:

The Auto Air Intake is working OK, as far as I can tell, with sensitivity set to "3".

(That's an improvement over the freaking-out it previously exihibited when I first tried tweaking it...)

Can't tell whether it is truly more sensitive (to "smog") than default ("0"), when set to "3".

(I guess I drive mostly in a relatively low-VOC environment nowadays...there is a large middle-class percentage here... )

Anybody else try this tweak? If so, any comments?

 

[Jim_Chow]

Speaking of the auto HVAC mode, the exhaust sensor only works when in auto mode, right? It seems like whenever I use auto mode, it turns on the AC (at least if I push the manual [climate] button, ithe nav indicates the AC is on despite the temperture I set the climate control to). Does anyone else find this to be the case?

 

[Tinkerer]

Speaking of the auto HVAC mode, the exhaust sensor only works when in auto mode, right? It seems like whenever I use auto mode, it turns on the AC (at least if I push the manual [climate] button, ithe nav indicates the AC is on despite the temperture I set the climate control to). Does anyone else find this to be the case?

In my experience with the '99 LX, the ambient air exhaust sensor (behind the front grill) & associated HVAC Auto Air Intake function only work when the Air Intake is set to "Auto", on the "Air Intake Control Button".

This is not the same thing as "Auto" setting of the overall HVAC operation - set by the "Automatic Control Button", at upper-left of the HVAC controls.

Two different "Auto" settings. Not to be confused. They can operate independently of each other.

So, for example, when the HVAC is operated in non-Auto Control setting, with manual settings of things like fan speed, Mode (Air Flow Control), Defrost setting etc., the Air Intake Control may be set to Fresh, Recirc, or Auto, independently of other settings.

This is great, if, for example, you WANT to have Auto Air Intake mode engaged, to automatically block junkmobile exhaust while using Defrost.

Many vehicles do not allow the driver to force Recirc mode when Defrost is on. The LX WILL allow that and also will provide the Auto Air Intake Mode while in Defrost - but not by default. You must set it so every time you engage Defrost mode, if you want it.

I believe I read in Slee's 100 Series writeup that an LX470 model year later than '99 had a different logic for the Auto Air Intake Control. Something about it forcing an auto switch to Recirc when smog detected even if the Air Intake Control is set to Fresh. Was that '03 LX?

 

[Jim_Chow]

[snip]I believe I read in Slee's 100 Series writeup that an LX470 model year later than '99 had a different logic for the Auto Air Intake Control. Something about it forcing an auto switch to Recirc when smog detected even if the Air Intake Control is set to Fresh. Was that '03 LX?

Yes, my '03 LX manual seems to say this. I'll have to play around with it, as this vehicle is still new to me and I only get to drive it once or twice a week.

I took it on my first long drive last weekend and discovered the steering wheel would need to be about 5-10 deg to the left when driving straight, yet the vehicle tracked straight. Brought it in today and the tech said there is a steering ECU update, not a toe/alignment issue, as the current ECU isn't sensing the steering center position correctly. I know the variable ratio rack steering was introduced in '03, and this is an early '03. I guess toyota accomplishes the variable gear ratio electronically. Luckily, it's covered under warranty (the extra money for the certified vehicle has probably already paid itself off). I could have lived with the slightly off-centered steering (prev. owner probably never noticed; since I drive holding the wheel at 5 and 7, one hand was gripping leather and the other wood ).

PS: the loaner RX ('06 w/ 1200 mi) doesn't come close to the build quality of the LX. It definitely has better acceleration and is more maneuverable, but the fit & finish don't compare...feels like a glorified Avalon, and there's a huge blind spot in the rear corner. LX is light-years better, feels a lot more solid when driving. My guess is the LS is of comparable build quality to the LX.

 

[Gohawks63]

Is this feature only available on the LX or can this be done with the late model LCs?

 

[Jim_Chow]

Although the auto air recirc function is separate from the auto climate control function, the '03 manual says if you manually turn off the A/C, the auto air recirc feature also gets turned off. So the only way to run the auto air recirc feature is to run the A/C w/ vent open (and why would I do that, as whenever the AC is on, it's in recirc mode for max. cooling?) . So it seems the only way to use the auto recirc w/ AC off is to have the auto climate control run everything and hope it's using outside vent air rather than the AC. Unfortunately, it seems everytime the auto climate control is on, the AC is also on, even when the recirc button is set to fresh, regardless of temp (as I push the climate button and the monitor indicates the AC is on). Anyone know when the auto climate control does not use the AC other than below 39F? (this was the only case when the AC didn't come on in auto mode).

I haven't driven the vehicle enough to experiment with all types of settings, as I can only do so much while driving, but ideally, I'd like to run the fan w/ recirc set to fresh but have it change to recirc mode automatically upon detecting exhaust, at least during the non-summer seasons.

 

[Tinkerer]

Although the auto air recirc function is separate from the auto climate control function, the '03 manual says if you manually turn off the A/C, the auto air recirc feature also gets turned off. So the only way to run the auto air recirc feature is to run the A/C w/ vent open (and why would I do that, as whenever the AC is on, it's in recirc mode for max. cooling?) . So it seems the only way to use the auto recirc w/ AC off is to have the auto climate control run everything and hope it's using outside vent air rather than the AC. Unfortunately, it seems everytime the auto climate control is on, the AC is also on, even when the recirc button is set to fresh, regardless of temp (as I push the climate button and the monitor indicates the AC is on). Anyone know when the auto climate control does not use the AC other than below 39F? (this was the only case when the AC didn't come on in auto mode).

I haven't driven the vehicle enough to experiment with all types of settings, as I can only do so much while driving, but ideally, I'd like to run the fan w/ recirc set to fresh but have it change to recirc mode automatically upon detecting exhaust, at least during the non-summer seasons.

Dunno about the '03, but the '99 allows forcing the Auto Air Intake function to Auto (VOC sensor -enabled) no matter what the other system settings are.

For example, if Defrost is selected, the Auto Air Intake switches to Fresh by default. But it can then be manually toggled back into Auto (VOC sensor -enabled), while Defrost remains selected.

As to AC or no AC: The '99 manual says the AC button toggles the AC compressor operation on or off. Haven't tried this. I assume that if it is toggled off, the main system "Auto" mode disengages and the system changes to a manual mode.

 

[Jim_Chow]

[snip]

As to AC or no AC: The '99 manual says the AC button toggles the AC compressor operation on or off. Haven't tried this. I assume that if it is toggled off, the main system "Auto" mode disengages and the system changes to a manual mode.

Yes, the AC does turn off, but it also turns off the auto air recirc feature on the '03, according to the owner's manual. I still need to experiment more. The electrical wiring manual doesn't explain the algorithm the auto AC ECU uses.

 

[Tinkerer]

Yes, the AC does turn off, but it also turns off the auto air recirc feature on the '03, according to the owner's manual. I still need to experiment more. The electrical wiring manual doesn't explain the algorithm the auto AC ECU uses.

That could very well be so. Generally, preventing the AC compressor from running while the system is in recirc mode is undesirable - this causes moisture buildup in the cabin, can cause the windows to fog up and funky odors to multiply.

 

[Jim_Chow]

That could very well be so. Generally, preventing the AC compressor from running while the system is in recirc mode is undesirable - this causes moisture buildup in the cabin, can cause the windows to fog up and funky odors to multiply.

I was thinking of the same thing, especially for cold, humid climates like most of the country when you have to crank your heater/defroster every morning and the windows fog up. But here in sunny AZ, we only see fog maybe once a year the morning after a rain, and it's only rained 0.01" in the last 5 months.