Sour Mildew smell from A/C

[Kokorone]

This new 6th gen has been the first vehicle I’ve had where the A/C on startup consistently smells like sour armpit when the car is started. I live in SoCal so it’s not like it’s all that moist here either. Not a huge issue, but definitely of note compared to the host of previous vehicles I’ve owned without this issue.

 

[donayre21]

check the filter. I did notice a wierd smoke smell in the trail hunter when I test drove it. Its normal for the first few miles since things are band new

 

[Nodak]

dont run the a/c and then shut the vehicle off. the moisture will smell if you constantly do that. best bet is to turn off the a/c before you get home and dry out the system before parking.


and take it off recirc if you can

 

[LLL1990]

dont run the a/c and then shut the vehicle off. the moisture will smell if you constantly do that. best bet is to turn off the a/c before you get home and dry out the system before parking.


and take it off recirc if you can

I live in the south and have never had a car with musty smelling A/C and don't know of anyone personally who's had that issue. And I haven't done this procedure since turning off the A/C in the summer will give you heat stroke in 2 minutes.

I can tell you that turning off recirculate will cause more moisture to build up on the evaporator, if the A/C is on fresh air water will flow out the drain in a constant stream. That's because it's dehumidifying the moist humid outside air being pulled into the evap. On recirculate it's pulling the cabin air back into the evap and after it runs a while that air is dehumidified and dry so there is not a lot of moisture on the evaporator. You will see much less water draining from the evaporator.

Maybe that's why we don't really have stinky A/C in the south, our cars run on recirculate and max a/c most of the year. Also the cabin temperature getting up to 140+ parked in the sun all day tends to dry things out.

 

[CuttingedgeSport]

It was common to happen on all our Toyota and Lexus cars in Colorado.
As previously mentioned, you have to turn off the ac and put it in outside air mode before arriving home.

You can also just turn the ac off and turn to fresh air when you get home and crack your windows a little.

if you have the smell recurring, turn your ac off, and your heat on highest temp at full speed in recirc mode and in fresh-air mode for several minutes with the windows cracked. You don’t have to sit in the car while performing this procedure.

This will usually burn off the sour mildew smell and you will find it much improved. A good quality AC cleaner treatment follow-up (factory Toyota or other)doesn’t hurt either. I believe like LLL1990, this is why my previous cars in the South didn’t usually smell musty, because it gets so frickin hot that it kills those bacteria.

All of this assumes a good condition cabin filter, no leaf litter or crud in the condenser, and a free-flowing AC condensation drain tube trickling out water while running.