I have an odd, intermittent issue. My car is fitted with an aftermarket Webasto parking heater, which turns on the climate control system once engine coolant is warm enough. For this, I have to set the climate control settings correctly before I turn off the car; airflow to windscreen or windscreen/feet, fan speed to 2/7 or 3/7, and most critically, recirculated air mode. Otherwise the car keeps drawing in freezing outside air.

Thus, I set the mode to recirculated, and make sure the LED above AUTO on that button is not lit. When I start the car next morning, sometimes it's very warm inside and the recirculated LED is lit, but during last two days, it's been quite a bit cooler and the outside air LED has been lit. The car appears to change this setting by itself, even though it is not in AUTO mode...
After selecting recirculated mode, I try to wait for a moment (for the physical flap to move in the system) before I turn off the car.

What could be the cause of this insurgency?

 

There is a smog sensor setting that controls that on earlier model LS cars. I've long past forgotten how to change it, but if you look in your manual you will probably see a setting to determine when to pull in outside air or when to go into recirculate mode. After 2013 they default to recirculate.

 

I'm aware of the setting, and I've set it to maximum sensitivity. Shouldn't it only have an effect when the air circulation is set to AUTO?

I've now tried activating air recirculation right before (less than 1 sec) I turn off the car, and based on two morning warmups, the setting has persisted. I'll have to do some more testing...

 

I just saw this setting today while messing with the settings. I think it was called smart circulation, turn that off and it won't change. It is a couple lines below the smog sensor line.

 

While I'm still not convinced that the smog sensor sensitivity would override manually set circulation mode, I tried putting it to its lowest setting, but it has made no difference. This week, the car has defaulted to taking in outside air every time I've started it, despite having set circulation before shutdown. This is getting properly annoying.

Thanks, but my car doesn't have that setting. If I hold the circulation button down, it will show me the smog sensor sensitivity setting, but there's nothing else on that screen. Is your car a later model?

 

This is the way the system is designed. It has a mind of its own when it comes to recirculating based on exterior temp

 

I cannot believe that, not when the button in question has an AUTO position as well. Why would it be there if the car switches between the two modes by itself anyway? If I put on recirculation without the AUTO LED being lit, it faithfully stays on recirculation until I the car is shut off and started again.

Just in case there is any confusion, this is the button I'm talking about. Here it is in AUTO mode, the car having chosen the mode by itself as it is supposed.


Here's a video I just shot; I've set it on MANUAL recirculation (no AUTO LED) yet it reverts to outside air on startup:

 

I understand that, that’s the way it’s supposed to work. The AUTO function is a smog sensor which chooses between the two settings based on air quality. The system decides what it wants to startup in though. In hot weather you’ll find it will always start up in recirculate regardless of what you have selected when you turn the car off.

 

When I was messing with tech stream a few months ago adjusting settings I think I saw one that allowed you to select between recirculate or outside air on startup. It may be in the personalized settings.

 

I just checked the FSM for the 460 and I don't see a setting in TS to select between recirculate or outside air on start up. OP have you tried to run the AC diagnostic test by holding the BIG auto button and the recirculate button while starting the car?

 

I hope my response sincerely helps you. Even though you set the recirculation mode to recirculated position, the system can still automatically turn itself to outside air (in the manual)....this will only happen when in windscreen or windscreen/floor mode. It is done this way to prevent windshield fogging. For some reason, some of the Toyota and Lexus models that are available, you are able to close the recirculation feature when using the windshield defrost, my 4Runner does this, same with our LX but the manual HVAC system in our two cars, it is fundamentally impossible to engage the recirculation features while setting the HVAC to windscreen or windscreen/floor. I have heard other brands prevent the use of recirculation in defrost mode, but for some reason Toyota allows you with cars that the auto climate control system.

My suggestion would be to set it to the floor position only, thus the recirculation feature will remain engaged.

ps. I had never heard of a Webasto parking heater....never knew such inventions existed until I read your thread.

 

Thanks for the explanation, that makes sense to me now I guess, as holding that button down shows the smog sensor sensitivity screen.

There's "Air Inlet Mode", I tried setting it to manual for now. Couldn't see a setting related to the startup position.


I'll try the diagnostic mode, thanks for the tip!

Thank you for this information. The main reason I'd want the windscreen position is to defrost the windscreen of any ice, and that is also instructed in the "end user manual" portion of the Webasto installation manual for the LS460/LS600h. It makes no mention of recirculation however, but I think it's a total no-brainer that the cabin will warm up far faster when the system is not drawing in freezing outside air...

I have a fairly comprehensive heating setup on the car; on a normal morning, 2 hours before I leave for work, a 10A battery tender and a 1000W electric cabin heater are activated. 30 minutes before I leave, the 5kW Webasto turns on (on a timer, but I can set through an app on my phone) and starts burning small amounts of fuel to warm up (and circulate) engine coolant. When the coolant reaches some pre-set value, 60°C/140°F or so I think, the Webasto activates the car's climate control unit, which starts blowing warm air to the interior.
A few rare times the recirculation setting has persisted, and I've been presented with a nice 21°C/70°F car in the morning. An unnecessary luxury I'm sure, but I hate cold.
Nearly always however, the recirculation has turned off, and the climate control draws in freezing outside air, as a result of which the cabin is at about 5°C/41°F.
This morning I set the climate control to its minimum fan speed, to minimize its cooling efforts, and the interior temperature was a nice 15°C/59°F. In essence, the $3k Webasto I had fitted is detrimental to my comfort unless I can get this car to behave.

About an hour ago, after I had set Air Inlet Mode to manual, I activated recirculation and turned off the car. After waiting for a minute or two, I started it again, and again it defaulted to outside air. After this, I also tried setting airflow to floor/face mode before setting activating recirculation and turning off the car, but again it defaulted to outside air on startup. I'll try the floor-only position later.

While only a handful of times, the setting has occasionally persisted, and I have no idea why. At some point it seemed as though shutting the car down within a second of activating recirculation might've done the trick, perhaps because the last thing it remembers was being asked to recirculate, but most of the time it's had no effect.

 

Living in Toronto I get the full range of tens over the year and I’ve found that when the HVAC is set below ~21 the system defaults to recirculating air.

Try setting to 22 and see if it persists.

I too would prefer it didn’t so even in the spring I set to ~21.5 to make it default to fresh air.

Once it gets warmer out and 21 is too high I get in the habit of hitting the button twice every time I start up...

 

I fully understand what is going on now. The only way to get air flowing to the windshield is to put on the defroster and when you put the defroster on the hvac automatically pulls in outside air. There's nothing you can do about this, like Steve said it's the way the car was designed. What temp do you have it set to when you exit the car? If your car is fully warmed up and your temp is set to hot when the Webasto kicks on the interior should still be pretty warm even when pulling in outside air.

 

When I exit, I set the temperature to "HI"; highest setting.

This week, I've started doing things a bit differently:
1) I've left the circulation mode to AUTO
2) I've stopped using the electric cabin heater
3) I've scheduled the battery tender time to be the 2 hours after arriving home instead of the 2 hours before starting in the morning
Despite it occasionally having been in outside mode when I shut the car off, it was in recirculation mode when I started it in the morning. I wonder whether the interior being colder (no electric heater) when it starts makes it choose recirculation on its own accord?

The battery tender timing shouldn't have any effect, I only changed it because a warm battery is more receptive to charging.

This situation is ok for now, though I'll do some more testing still.