Moldy smell when fans turn on

Yes, it's a known issue in Toyota's for years now.

Master Toyota mechanic "The Car Care Nut" has a video on how to disinfect the A/C system. But, in the meantime, he suggests you turn the A/C compressor OFF when the car is done being used for the day and blowing the fan on HIGH for at least 5 minutes as you are parking it. This dries out the wet insides of the A/C system which can help prevent the nasty smells.

Also check your cabin air filter, make sure you have a carbon activated one. If it's not, replace with one. (I don't spend the crazy expensive cost of a Toyota OEM filter, I like the Fun Driving charcoal filters they sell on Amazon...for our 2017/2021 Prius, it's $22.48 for 3 of them.

 

Just typed in another thread:

Cabin / Air Filter Combo | Page 2 | PriusChat

 

I saw that, Mendel...thanks! Seems to be a common complaint with Yota's around this time of year!!!

Have you ever done one of those Toyota A/C disinfectant jobs? I never have but if they aren't too hard I might be inclined to clean our 3 Yota's before winter comes.

 

A filter replacement isn't going to take care of this issue. You have mold spores all around you. All they need is a cool, damp, dark environment to grow in. Your AC evaporator is the perfect spot for them.
1. Check your filter & evaporator drain. Make sure they're not clogged
2. Place the climate system in manual mode. Temp. 68-72 degrees, fan on low
Whenever you use the AC, turn off the compressor 5-10 minutes before you reach your destination. That will dry out the evaporator area and prevent mold from forming.

Hope this helps...

FYI: That's how I've got my car setup, never any mold smell...

 

try turning off the a/c a mile or so before your destination

 

You need this injected into your condensate line with the cabin filter removed. Works.

 

Here's an official video on how to use the above product:

 

The problem is often worse in humid locations. Keeping the cabin filter reasonably clean limits organic material in the evap coil.

The foam is all I use. The other can is fragrance. You can do the foam by jacking up the front passenger side and using a jack stand for safety. To make it easier after the first time, I add a hose splicer and extra length of hose routed to the passenger wheel well for easy access in the future.

 

No, always followed my advice: sparing use plus turn it off a mile before destination.

It’d be welcome if someone would address this. Say something that vibrates the evaporator for a second or two whenever the car’s shut down, or heats it to drive off the moisture. Something… plus make the thing readily accessible, flexible hoses and capable of dropping down/out for cleaning.

 

Newer auto climate systems might do a dry out cycle on their own.

 

If you keep organics out of the coil there is nothing for the mold to grow on. Using recirc most of the time helps even when a small amount of outside air continues.

If it is not routinely humid, condensate and organics are rarely a problem. The foam cleaners work well and have generic equivalents at auto supplies. I have probably cleaned my coil 3 times in 12+ years of Texas heat and humidity. It is one of the easiest diy tasks.

The dirty sock syndrome was far worse before cars had cabin filters. Evap coils would routinely get severely clogged impacting air flow and capacity.

Home ACs can have the same problem and have the same solution, quality filters and periodic coil cleaning.

 

Actually read the manual for a new portable AC unit. It instructs to run in fan mode for a some time before storing to dry out the coils.

Regular use of fan only should prevent mold, but you'll likely have to clean it if mold is present enough to be smelled.

 

They do, which is why it's hilarious to read some of these posts.

User: "Toyota should do something to prevent moisture buildup."
Toyota changes A/C programming in new models to reduce moisture buildup
User makes A/C control choices that circumvent the programming changes
Moisture problems continue
User: <surprised Pikachu face>


In other words, the gen3 and gen5 are not the same car, and techniques that were useful on the gen3 may not be needed on the gen5.



Plus, we all ignored part of the OP's post: THIS ONLY HAPPENS WHEN THE CAR IS PARKED AT ONE LOCATION.

Before we all jump to the standard diagnosis of condensation in the A/C box leading to mold buildup, I think more questions need to be asked and tests tried.

1. What are the conditions in front of the garage? Sunny? Shady? Is there plant life or animal life nearby?
2. Is it actually the location that's causing the smell or is it the driving habit? Try driving the same routine, but park in the street or something instead of parking in front of the garage. Does the smell return or not?
3. Do you have a camera with recording capabilities watching the driveway? If so, watch the recording to see if animals are approaching the car at night.

While I agree that the most likely scenario is a A/C box that isn't completely drying out, we shouldn't ignore the possibility of the car sucking in smells from plant life near the garage or animals using the car as a nighttime home.

 

When its really hot, since we only have garbage collected every other week (recycling and compost is weekly), if we have kids diapers in the bins, sometimes my car smells real bad for the first little bit when we drive.

Happened in the old car too.

It is, for us, just because the garage can get smelly in summer. It's entirely possible theres a location based reason for OP too that has nothing to do with the car itself.

 

I use the auto mode on mine and in less than a year I got the smell from the AC on startup. It currently only smells 10-20 seconds on start up after the car hasn't been used for a while. I'm looking for one of those cleaning kits to try it out before it gets worse. I am not a fan of the system using the AC regardless or whether I press the AC button or not. Getting outside air through the vents is more of a hassle in this car than any other I've had.

 

Press the AC button once or twice until the light is off, then it will be disabled. And it will stay disabled until you press the AC or AUTO button again.

Only real confusion here is that 'light off' could mean either off or auto.

 

With our Canadian spec 3rd Gen, even with the light on the AC button off, if vent mode was in heat/defog (directing air to windshield and feet), the system would do “stealth AC”. I was monitoring AC wattage with a Scangauge.

 

I am surprised that they can't just have the light on the AC switch come on and off whenever its active.

 

It’d be going on/off all the time, might get tiresome.