Should I be using my recirculate air button often or only in certain situations?

Posted by MammothSal@reddit | askcarguys | View on Reddit | 42 comments

I only use the recirculate button for a few minutes if it's really hot to cool my car quickly when I first start it or if I know theres clearly gonna be an odor or smell ahead, like smoke or fuel etc.... Then I'll return to fresh air mode after a few minutes regardless if I'm using AC or heat.

I never use it for long periods of time basically and only use recirculate air for short bursts if needed. Like you know... 5-10 minutes at most ... if even

Sometimes I wonder.. is it healthier to use it more often?. Like should I be using it anytime I'm in heavy traffic to protect myself from air pollution? Am I overthinking this? My manual says to only use recirculate for short periods to "prevent drowsiness "... which I find interesting as well lol... recirculate air for less pollution being pulled in while in traffic or let my self get drowsy from recirculating the air too long?? lol.

Idk , sorry for the weird question.... when do you use the recirculate air option?

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_EnFlaMEd@reddit

I use fresh until the cabin starts cooling then recirc. Takes ages to cool down otherwise.

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BouncingSphinx@reddit

My first car manual specifically said to use fresh air with windows cracked for a while to help replace the hot air rather than trying to cool it at first.

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Stock_Block2130@reddit

Exactly. Read your car manual. I open all the windows and drive for a block or two to get the worst of the hot air out. Then AC with fresh air intake and finally recirculate after car has cooled down fully.

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Gian_Doe@reddit

The 'max ac' option on mine turns on recirc only, so it's the opposite for me. Windows down for a block or two on 'max ac' recirc until it cools, and then switch to vent.

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Stock_Block2130@reddit

That’s why it begins with check your car manual.

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Gian_Doe@reddit

Right, my point was I'm surprised yours says the opposite because they all work on the same principle. The AC in a car is very powerful, on a hot day the air inside the car is going to be cooler than the air outside fairly quickly.

It's counterintuitive. What model car?

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Stock_Block2130@reddit

It’s a VW Passat. Manual says to begin the AC on outside air if the inside of the car is hotter than the outdoor air. Then switch to recirculating once the interior has cooled down. Makes sense to me. And I have always opened the windows first to flush out the worst heat.

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BouncingSphinx@reddit

Max A/C has virtually always switched to recirculate to be able to cool the cool air even more rather than cooling warmer air from outside. Just the way to get it the coldest it can be. But mine basically said for initially it’s quicker to cool down external air and let the hot air escape than to work to cool the hotter air inside, then turn on recirculate to cool the now cooler inside air. Hot air rises, so letting it escape from the cracked windows just makes sense.

ChrisGear101@reddit

The car doesn't care, and neither way is better or worse. One recirculates cabin air, one brings in outside air. Its just a flapper that opens or closes. So use whichever you want based on the situation.

NuclearHateLizard@reddit

Yeah that's really all it's there for, or if outside air is undesirable, like smokey, , high moisture, smelly etc

Ok-Huckleberry1970@reddit

I use it because i feel it helps get the temperature i want faster. I have yet to get drowsy from driving with recirc on for 6 hrs at a time. Plus it helps so cabin air filter doesnt get too dirty

mnth241@reddit

In Florida i drive with it on 100% of the time! Why do i want 95o air coming in my car?

Even now (midwest) the outside air seems smelly and dirty.

Dang now i gotta go find my manual.

bobbycalamari@reddit

If you press and hold zero (0) you get a ° symbol

Valuable_Cause9119@reddit

I’ve gotten headaches and tired from it on recirc for too long. I do use it to get to my temp though

Meguwubie@reddit

3x I 445666888⁶to the 6 50k 86speed 332

2ndOpinionAutomotive@reddit

Auto functions are typically the best because they will account for outside temp and inside temp to determine what is best and will prevent windows fogging up and such. But rule of thumb - recirc should really only be used in the summer time with AC. If your windows are fogging up, turn recirc off.

Wolf_Ape@reddit

A lot of people seem to have way more confidence in the air tight cabin integrity of their vehicles than could possibly be merited.

Aside from the large 2-4 large openings for flimsy plastic cages with tissue thin rubber diaphragm sheets that prevent pressure spikes from slamming your doors, there is +/-50 linear feet of door sealing surfaces before considering windows, trunk/hatch or sunroof, countless drain plugs and openings for wire bundles under and behind every surface starting just below the windshield that spans the entire chassis all the way back and up to your tail lights. You will not run out of breathable air even if you tape up all your vents.

Drive your car into water and it is only partially buoyant, and not for all that long.

Exhaust leaks are only a serious safety concern because of how easily the fumes can rise up through the floor into the cabin.

Yes there is a certain automaker that has claimed his cabin air designs are a hardened nbc (nuclear/biological/chemical) filtration system, but he also said the cybertruck is an indestructible armored beast with unbreakable windows. That is the exact same category of nonsense claims in an attempt to appeal to the weirdly specific sword collector/survivalist ev buyer demographic that he identifies with.

scott9ssd@reddit

Use outside air when you first start up the car then after a few minutes, use recirculate.

Neat_Establishment70@reddit

You should use it in conjunction with the window lock button after farting with your kids in the car.

soupcook1@reddit

I manually use it when following a smelly vehicle or passing through an area with odors. Otherwise, I let the Auto A/C manage it.

tallwater333@reddit

Yes, my auto feature switches recirc on/off automatically.

Camo138@reddit

My recirc button broke

TheHotJesus@reddit

Could it be the servo motor that changes recirc to open broke? Depending on vehicle, it could be a cheap and easy fix.

If the vehicle has been baking in the sun, open windows for a few minutes and let the hot air out and AC to get cold. Then close windows and switch to recirculate and let the vehicle to cool down, then auto

Glum-Welder1704@reddit

I use outside air unless the AC isn't keeping up. Then I'll switch to recirculate so the air entering the AC will be cooler. Outside air is usually dryer, and better for defogging windows.

LexusI@reddit

Man, I never have changed this on my cars…always recirc with windows up and after many long trips and millions of miles I am still here. I am a survivor.

Not like pressurized air plane cabins, right? I figure my car wouldn’t try to kill me and will bring in fresh air when it deems appropriate lol.

SailingSpark@reddit

I know my landy, a 2003 Discovery, turns off recirc after 10 minutes.

CONKERMANIAC@reddit

I always have recirc on because I have wanky hayfever for 4/5 months per year.

Onlyunsernameleft@reddit

It realistically doesnt make a huge difference. The only instance in which you'd want to be mindful of it is on a long trip. After a while the oxygen in the cabin will be spent and in recirculation mode, no fresh air/oxygen will enter the car. So if you were taking a trip where you're driving for a few hours, you would want to crack a window at least to let some fresh air in or you would want revert to outside air circulation.

9BALL22@reddit

You're using it correctly. Using recirculation doesn't completely shut off outside air, but it does eventually reduce the oxygen level. This has the same effect as it does on an airplane, fatigue, sleepiness, possibly nausea, ect.

foolproofphilosophy@reddit

Auto or rarely. You’re trapping moisture in the car when you leave it on recirculate. You can also use the AC to get moisture out. If your AC turns on with the defroster do not turn it off.

TheChinchilla914@reddit

Cooling air inherently dehumidifies it (cool air can’t hold as much moisture)

Numerous_Historian37@reddit

Older cars sometimes had a "dry" or desert only setting(AMC) for AC. This uses recirculation to extra cool the air inside. The reason they don't want you to use in humid environments, the AC evaporator freeze that moisture making the AC not work at all until it thaws.

Modern cars should kick the AC compressor off before this happens, so shouldn't ever be an issue.

i2px@reddit

Totally wrong. AC air is dry, that remains true whether or not the air comes from outside. Secondly, every car I have ever owned has opened the recirc vents when shutting down.

FutureHendrixBetter@reddit

I have mines open while the car is moving at decent speeds but close it at a standstill/ stoplight

Nervous_Hurry_9920@reddit

I use it 100% of the time. I'm not trying to smell city smells.

RandomGen-Xer@reddit

Do what makes sense for your comfort in the moment.
Mine stays on recirculate the vast majority of the time.
Except when we go through the car wash. We love those smells :D

cormack_gv@reddit

Recirc for max AC. Never for heat.

chonas76@reddit

I have no idea if I use mine or not. I’ve got a 2016 Silverado and I just set my thermostat on auto. The only thing I ever adjust is the temp I want

CakesForLife@reddit

I usually recirculate most of the time - but if it’s longer journey (with other people) I would recirculate on and off.

I know that post 2010s BMWs switch to recirculate (for 30 seconds every 30 mins - or something like that) even when you have forced it to be on recirculating only. Other automakers may have something like that over the 10 years or so too.

gonzal2020@reddit

You are overthinking it.

The way you use it now is fine.

Recirculation air still has to pull fresh air periodically from outside or you will eventually breathe very contaminated air. So you are breathing polluted air whether or not you want to. Only solution for that would be to carry oxygen bottles around with you.