After turning my AC off today, I noticed a cold mist coming from the AC vents for a short period. Vehicle has 2,400 miles on it. Any ideas? I’ve never seen this phenomenon with any of my other vehicles before. I am guessing there is a leak of sorts and the mist is some evaporated fluid?

I know it’s very common for cars to drip condensation after running the AC, is this perhaps condensation that evaporated through the vents? The vehicle was in a parking garage at work all day, and it was 84 degrees when I started driving home from work. Fairly short drive. I typically run the AC at the coldest setting available, but will tend to have it blow at low settings. Either 1 or 2 clicks on the knob from the off setting. I also use the setting that does not circulate air, but instead brings in air from outside.

Edit: just read that not using the recirculated air button makes the AC work much harder. I have always used the outside air option without exception on all my cars (which were all Hondas before this 4Runner). Never had an issue with AC before. Even on a 10 year old Honda.

check the condition of the cabin filter. Running the fan without the ac on for a minute or two before parking the car will also dry out the filter of any condensation.

Ok, will do.

Never use outside air when using heater or ac in this part of the world. I see it as just getting pollution into your cab from other vehicles that are close to you and might be causing more dust to accumulate in your filter. 3rd gen not to worry 3rd gen best gen

Yeah, you're not wrong. Unless out in the middle of nowhere or if a passenger has gas, I'll stick to the recirculation option. I also did not realize that the recirculation setting chills the vehicle faster. I mean, it makes sense now that I think about it, but the idea had not occurred to me before.

When its hot and ac is used, I like to first open the windows and get that hot air out with the ac turned on. Air inside a hot vehicle is hotter than the air outside of it. Factor in a dark colored vehicle and it may be even hotter.

Once a little airflow has happened close up those windows and put the ac on recirc mode. (not a fan of the mildew smell that can pop up)

As for frosty air coming out of the vents, that can happen on very humid days if sucking in air from the outside.

I've had misty air coming out of my vents on multiple Toyotas, not at all unusual. It's condensation on the evaporator,nothing to worry about. It's worse when it's really humid inside the car. Think of when you open the freezer door on your fridge and all that smoky, cold air comes out; same thing.

Re-circulation is better with A/C since it's drawing air from the cabin, which is getting increasingly cooler as the A/C works. Outside air will stay hot. If my A/C is freezing me out then I switch to outside air for a while. Of course, this will put more moisture in the cabin and cause more misty air from the vents.

Put a thermometer in the A/C vent. If you're between 42-50° then you're fine. It will cycle on-off and the temp will fluctuate; normal operation.

On the Tacoma forums people report using recirculating lot can cause excessive moisture build up and funky smells to develop/last

Interesting. I may have observed this on my wife's Lexus CT.

When high humid air flows past ac coils it can create a vapor mist sometime. Most of the time the the humidity collects on the AC coils and then it drops into a disposal tank below. Once the car stops it drains onto the street.

The AC works as a great dehumidifier. In the winter if your windows are all fogged up run the ac on with the heater with the vents closed. It will clear it up your foggy windows very quickly. Once it clears up stop the engine so the water will drain. Then turn it back on. If you don’t do this the water may sit in the disposal tank and the moment you turn the ac off while running the heater, the heater will warm up that excess water and put the humidity back in the car. If you are driving then just leave the ac on the whole time.

Note: you can’t do this in defrost mode. Toyota won’t allow you to close the air vents in defrost. In the winter time Toyota thinks the outside air is dryer which is generally and by keeping the vent open it will eventually push the humidity out which usually works. This will also help defog your car windows but it takes longer. The problem is on warm rainy days when the humidity is high. Trying to use the defroster to clear the humidity off your windshield doesn’t work well because the vents won’t close.

I didn't know you had warm days in SF

Here in the very high humidity and rain we have to use the defroster mode and turn the temp up depending on the outside temp.

Note that all manufacturers run the a/c in defrost mode in addition to any heat for the express purpose of lowering the interior humidity.
Be aware that warm air holds more humidity which also reduces window fogging.



Or you could just turn down the fan speed and/or adjust the temp knob to a higher temp.

BTW, at home I never open windows, I just adjust the thermostat to control the temperature.

That’s true but I live on the very outer edge of the SF Bay Area. Much warmer out here. On a warm summer day it can get up into the mid 100’s and SF will still be in the mid 60’s. Burrrr, no thanks, I like my warm weather.

My last car didn’t but it was almost 20 years old.

You have a good AC. Nothing more.

If you were in a hot humid environment and you start the AC, sometimes will smoke/vapor a little bit until your AC removes some of that humidity. I can make that happen at will on my /14. If I'm taking a road trip and the vehicle is getting a little too cool, I can turn off the AC completely for a few minutes. When I start the AC the extremely cold air will smoke a little.

I can also do it in my 20 year old truck. I have a heater core leak so I disconnected the heater core. I have ALL AC all the time whenever I run it. I can't modulate the temperature at all. If I get cold and turn off the compressor, it will slowly warm up the cabin. When I turn the air back on it will push fog for maybe a minute as it starts to dehumidify and cool the interior.

Your AC evaporator needs to be replaced. Or cleaned out. In the black box behind the glove compartment. Evacuate the Freon and replacing the evaporator is ideal. There is no in cab air filter so that thing gets 🤢

Toyota sells a AC foaming kit that will clean the inside of your AC. I would give this a try first before replacing it. Here is a link on how to do it.

Trail Maintenance: 5th Gen 4Runner A/C Refresher Service

CarCareNut-Here’s How To Fix and Prevent AC Bad Smells

I think 3M makes a kit too.