Air recirculation

Anyone know what the purpose of eliminating the ability to recirculate the air when set to defrost? It's always been something that's frustrated me, and I see that this isn't limited in other vehicle I've been in. For example, this morning being behind a bus and smelling diesel exhaust, but it's too cold to switch defrost off so I can set to recirculate, super annoying.

 

Hmmm... Didn't even notice that it was disabled in defrost mode. I'll have to check the next time I drive the 4Runner.

 

I believe outside air is dryer and is better for clearing up fogging over recirculated air.

I don’t think I’ve driven a vehicle that didn’t automatically switch to outside air for defrost since my 98 Sienna’s manual selection lever.

 

I have noticed this as well. In my small mind, I believe the most logical reason to not be able to recirculate inside air with defrost is likely due to the assumption of ability to get rid of inside humidity using the air conditioner compressor and outside air. Having the air conditioner compressor operate in defrost is the most effective dehumidifier.

 

Did a little digging around and seems like several of you are on the right track. The inside air has more moisture, so recirculating it would be less effective than pulling air in from the outside. Warm air also carries more moisture, which is why the AC is even more effective at clearing the windshield, essentially throwing outside, cold, dry air at it.

Just wish there was an option for when I don't want to smell what's outside but need a little bit of defrosting to keep the windshield from fogging up.

 

^Use a cabin filter with activated charcoal or carbon. I use TYC P/N 800012C with good results. Fram Freshbreeze with baking soda works even better, but restricts airflow too severely.

I notice recirc gets the windshield foggy after a while even when not in the demist setting. That's why every vehicle I've been in sets fresh air mode and turns on A/C when selected to demist.

 

^I was just editing my post with part numbers.

 

I also use a cabin filter with activated charcoal or carbon.

 

Rock Auto shows it's applicable to 2010+ 4Runners. I'm using one right now, fits fine (old Fram removed on the right, TYC still in shrinkwrap on the left):

 

Keep in mind that the “Defrost” setting contributes to satisfying two scenarios…

“defogging” the interior glass of moisture and “de-icing” the exterior glass when it’s wet and frozen.

this is why recirculate is not available. It allows a single setting to “fix” both scenarios. (I think)

 

^3rd gen Tacoma got an electric PTC heater in the HVAC ductwork, so heat is available well before the coolant warms up. Maybe 6th gen 4R will get it too.

 

I could’ve sworn us 5th gen’s had one! Or at least I read it somewhere

 

I know in my Tundra (2011) I could set the defroster on lower heat and defrost and hit the non-recycled air button and it would stay that way for 5 to 10 minutes and then turn off (or did I have to hold the recycled button for 10 seconds, been too long). I have not tried this with my 4Runner. I never notice a difference when doing this on the Tundra on how quickly the windows defrosted. I also had the Winter package on my Tundra so it had the lower wiper heater on the glass as my 2021 ORP 4Runnner has.

Steve

 

Check for debris like leaves in the blower motor. Stock OEM blower motor only has a faint fan running sound to it at speed 1.there is no ticking from the fan at any speed.
Alternatively, just swap for a new motor to see if the ticking goes away.

 

I had a ticking sound that came and went, due in part to debris inside the blower fan unit AND contact with the air filter of all things.

 

Same issue here, with music off I can hear the motor whining/buzzing away softly at Low speed but quite audibly unlike every other vehicle I've daily driven, Toyota's and others.

No debris, the dealer swapped the motor as a sorta-goodwill repair (at the cost of a pricey cabin air filter - no comparable 4Runner available for me to check) and no change sadly. Not sure what's next other than living with it.

 

These things work really well here where it gets humid.

$23 wisedry 2 x 500 Gram [2.2 lbs] Rechargeable Silica Gel Car Dehumidifier, Microwave Fast Reactivated Desiccant Packets Large for Gun Safe Closet Basement Garage Storage Moisture Absorbers Bag Reusable

https://www.amazon.com/gp/product/B0781BR7V7?ie=UTF8

 

Surprising number of models are interchangeable with it, GX460, LS460, Avalon, Venza, JL Wrangler, 2013+ Range Rover...: https://www.rockauto.com/en/moreinfo.php?pk=10863284&cc=1445667&pt=6916&jsn=460
https://www.rockauto.com/en/moreinfo.php?pk=3525402&cc=1445667&pt=6916&jsn=464

 

This is one of my most hated 4Runner features.