New and old Tesla Model 3 owners have been turning to the good old internet to find out why their EVs develop a nasty smell from the AC system. After just six months of taking delivery, one person asked for help on Reddit, complaining about an unpleasant odor when the AC fan starts, which is not very confident-inspiring.

As it turns out, it’s a common problem on the Model 3, and the most common fix presented in YouTube videos and on forums is simply to replace the two cabin air filters and spray a solution on the condenser when it starts to stink inside. But that doesn’t actually address the root cause, just the effect.

 
 

And here’s where the video embedded above, published on YouTube by Adam Davenport, comes into play. Frustrated with the usual go-to solution, he got himself a moisture meter and put an action camera to good use.

The GoPro went inside the plastic duct that directs fresh air into the AC fan, while the moisture meter was used to check how wet the two cabin filters were before and after washing the car.

The meter showed a percentage of about eight to ten percent moisture in the filters before washing, but after a quick spray on the windscreen, the meter went off the scales, showing “Overload” on the screen.

After reviewing the video footage from the GoPro, Adam found out that water goes through the fan and directly onto the cabin filters, especially when the fan speed is set to maximum. This happens despite the fact that the air duct has a drain hole.

Water getting into the AC fan when the speed is set to maximum.

So, what’s the fix?

The YouTuber offers several solutions to this inconspicuous but potentially annoying problem. The first is to simply remove the plastic air duct. This way, the water that inevitably gets to the plastic grille under the windscreen will no longer fall down the duct and instead, it will just drain next to the wheel well. There’s a metal grille that protects the fan, so this method can’t do any harm.

Another solution would be to use the Model 3’s Car Wash Mode which can be enabled via the central touchscreen. When it’s turned on, a plastic cover protects the cabin air inlet and doesn’t let any water reach the filters.

Additionally, there’s an aftermarket gasket for the upper part of the bonnet that replaces the factory version and offers more protection. However, water can still seep through the plastic cover that’s between the bonnet and the air duct.

Finally, the simplest solution is to keep the fan speed at a low setting. This way, it doesn’t create negative pressure inside the duct, and the water drains as it should. With this being said, it’s an approach that might make the windows fog up if you’re driving through rain.