Bam. This. Everything made worse if you live in a humid area.

Here is a search you may want to try on this forum.

A/C Evaporator De-Stinkifier

I bookmarked it in case I was having a problem.

Best of luck.

"Everything made worse if you live in a humid area."

I've had some stinky AC (from improper airing out) in cars ranging from a '67 Chevelle to a '78 Datsun B210 and an '86 Subaru 4WD wagon.

I assumed everyone knew this or learned it the hard way. I've mostly lived around Baltimore, D.C. and Richmond. Heck, we're officially a humid semi-tropical climate.

I get nosebleeds when the humidity gets under 40 or so.

"Average Humidity
Daily Place Morning
67 Lynchburg 79
69 Norfolk 78
70 Richmond 83
65 Roanoke 77"

One treatment is to leave the AC running on high and recirculate and spray a bottle of OZIUM in the car and slam the door. With the windows up of course. Come back later and see what you think.

I have never done this and I have never had smelly HVACs.

However, I have not yet used the AC in my 4runner as I bought it in December and it is my first Toyota, so perhaps they are different.

I thought Hawaii had high humidity and never done this and never had a problem.

Its humid here in the summer and I've never heard of anyone running warm air through, all that would do is put the humidity back in the vehicle. The condensate should drain, clear the drain if you have odors.

Go figure, Hawaii isn't all that humid if you believe the internet... compared to Richmond anyway.

"Average Relative Humidity in Hawaii
Lihue, Kauai Honolulu, Oahu
May 74.8% 66.0%
June 74.0% 64.8%
July 74.0% 65.0%"

Must be the breezes. I dunno.

It's like south east Asia here in the summer months. Even a month of no rain the humidity is over 70 usually in the 80s. Basically it will rust plastic... plus the winter freeze and thaw cycles, those rust the cars out.

My wife has a Tahoe and gets the smelly AC issue. She takes it in to the dealership and they run an "AC cycle" when they change the oil. My understanding is its an AC setting that runs varying heat and AC temps for about 20 minutes. It kills anything in the system and we get it back and the issue goes away for about a year...

I wonder if Toyota has a built in AC cycle they can run...

I've had this musty, moldy smell coming from my HVAC system since the day I bought my 4runner in 2015. I live in an area with a moderate climate. I only have the smell when I am running the fan only.

I rarely use the AC and when I do it's definitely not blasting or turned to the coldest setting.

I also keep my driver's side window down often during the warmer months and leave a couple of the other windows cracked or halfway down so outside air circulates well through my vehicle.

When I first smelled this I thought it was just some type of odor from the plastic from the vehicle being new but here it is almost 4 years later and the smell still exists.

Even if Toyota agreed to do something about this I don't think I would take my vehicle into the dealership and let them start tearing the dash and HVAC system down. I would probably come out with the same problem and then have all of the added squeaks and rattles from having the dash not installed back properly.

Never heard of running your system with warm air or whatever everyone is talking about and never done that either, and I live in San Antonio. It's not Houston humid, but it's humid enough most of the time and I've never had a problem.

it's always humid in FL...I've run my A/c consistently since I bought my 4R back in August of last year..used the heat a bit this winter, but my A/C is pretty much always set to on, only difference is whether I'm using the recirc.. I'm not experiencing any unusual odors from the A/C..

i'm trying to understand how running unconditioned air over the evaporator prevents odors and doesn't just put that moisture back into the air. the vehicles air conditioning is doing both sensible heat removal (basically just temp) and latent heat removal (energy, basically humidity). the coil cools the air to a low enough temp that it's basically at 100% RH, so the extra moisture condenses out and is supposed to drain away. if the drain gets clogged, that water just sits there and contributes to mold and odors. dirt and dust can also help hold water (and clog the drain). all running unconditioned air over this coil would do is allow some of this moisture to go back into this no longer fully saturated air and back into your vehicle and make you feel sweaty again, it does nothing to the help or fix the draining issue that is the cause of odors.

i haven't done it yet on the 4runner, but generally cleaning is a pretty easy process and you just need cleaner spray and some tubing. i'd bet toyota even has a kit.

I had to do that, but I am in Houston. It happened after the first summer here back in 2014, and hasn't happened since. Just cranked the AC and sprayed a ton Lysol though the ac air intake in front of the windshield and I never had a problem again.

I’ve used the Toyota AC refresher kit, cheap and easy and makes a nice difference for you have any smells. It also helps to replace the cabin filter regularly.