Manual Recirculated air switches to outside air by itself???

[artofwar]

I have a 2011 LE-4 Cylinder, and have started to notice that my manual ventilation system now switches from recirculated air mode to outside air mode after a few minutes on its own? WHen starting the vehicle up from cold, the setting now always starts from outside air mode (even though when it was set at recirculated mode when I last shut off the vehicle). When I purchase the van back in May, I never noticed it switching to outside air mode. I always left it on recirculated air mode and it stayed there. Only in the past few weeks/months have I noticed it doing this. I also cannot set the ventilation to work with recirculated air mode AND front window air defogger mode as well.

Does anyone experience this strange phenomenon on their vehicle?... assuming you have the LE model with full manual ventilation control? I wonder if there is a problem with the switch?

[Biggoldfish]

Originally Posted by artofwar

I have a 2011 LE-4 Cylinder, and have started to notice that my manual ventilation system now switches from recirculated air mode to outside air mode after a few minutes on its own? WHen starting the vehicle up from cold, the setting now always starts from outside air mode (even though when it was set at recirculated mode when I last shut off the vehicle). When I purchase the van back in May, I never noticed it switching to outside air mode. I always left it on recirculated air mode and it stayed there. Only in the past few weeks/months have I noticed it doing this. I also cannot set the ventilation to work with recirculated air mode AND front window air defogger mode as well.

Does anyone experience this strange phenomenon on their vehicle?... assuming you have the LE model with full manual ventilation control? I wonder if there is a problem with the switch?

I think the ventilation system is using outside air to prvent fogging up the glass. It may also be a safety issue. The system wants fresh air to be blown into the cabin just in case there is a exhaust leak into the cabin. And who wants to breathe in exhaust?
The issue of not being able to set the vents to recirc and defog is normal. The whole point of having a windshield defog is to make the glass clear enough to drive. To recirculate the warm moist air from inside the cabin and blow it onto the inside of the windshield defeats the whole purpose of defogging it. Especially during the colder days. Ever breathe on a window? Does it fog up? Same principle. My rule of thumb is: When the outside temp is colder than the inside of the cabin, turn on the defogger so I can see when driving down the road. HTH.

[akphs]

As biggoldfish notes, it's normal nowadays for defrost to force outside air.

ObAnecdote: in 1986 I bought my first brand-new car (after a series of beaters), a first-generation Legend. Was all excited about having things like power windows and *gasp* air-conditioning. I distinctly remember driving in the rain with my then-fiancee and thinking that recirc+A/C+defrost would be the hot setup to keep the windshield clear. Wrong: it started to fog badly until I took it off recirc. Seems humans breathe out more moisture than you'd think.

As for it switching to outside automatically on startup, that's also common (my last few vehicles worked that way), though I disremember whether the Sienna does this (will check later today on our Limited). Are you sure you aren't leaving it on defrost, which would of course run (and start up) in outside air mode?

[Electrical_Tech]

It fogged even with the AC on? Wow. Something our 98 Accord and 05 Sienna both did is when you select the defrost/defog function it automatically turned AC on (not recirc though). I haven't really paid attention to the recirc setting in our Tundra or the new Sienna, but I know on two F150's I've driven as company trucks .. if you have the setting to anything but vent (face vents) the recirc won't stay on (even with AC on) and even if you DO have vent selected, it won't stay on unless the AC is also on.