Best mode for HVAC to prevent mold buildup

[Chrisuoft]

With the warmer weather, I wanted to ask which method would be best for preventing the wet sock smell we all dread. I have a pre highland m3 with heat pump.

1) run in auto mode all the time. Is it confirmed that upon parking and exiting the vehicle, the HVAC will continue to run without AC enabled for a few minutes? When I leave and park my car in auto and walk away, the car seems to be off and I don't hear any of the HVAC fans running.

2) run in manual mode, but turn off AC mode five minutes before arriving home. Presumably turning off AC but allowing the fan to run will achieve the same thing as running it in auto mode, and I prefer the manual adjustments I can get with manual mode.

Thanks for the insights!

 

[timothydog76]

I'll share my experience with the dreaded A/C smell and how I think I've fixed it. I've done the HVAC settings and blasting the heat for an hour thing but the smell would always come back.

I've had my 2018 LRM3 almost 6 years and I think I've replaced the filters and used the foam cleaner 5 times from the awful stink. Last year I watched a YouTube video of a guy doing some testing on what exactly is happening and his conclusion was the bottom of the stock filter is wicking water that might collect at the bottom of the tray (even if it is draining properly). He would use a moisture meter on the bottom of the filter and you could see the filter was damp after most of the tests. Last time I ordered filters I went with aftermarket ones that have a plastic shell around the sides instead of the stock ones that are just unprotected filter paper. It's been almost exactly a year and I have had ZERO smell. Usually I couldn't make it a month into a rainy spring season without the smell coming back but here we are in June and it's been fine.

 

[Jangy]

Often changing of airfilter element and cleaning of the chamber is the only way to keep it clean. The procedural stuff doesn't work. How "often" you need to change is based on relative humidity in your area. I go every 6 months if it has been humid/wet

 

[stopcrazypp]

With the warmer weather, I wanted to ask which method would be best for preventing the wet sock smell we all dread. I have a pre highland m3 with heat pump.

1) run in auto mode all the time. Is it confirmed that upon parking and exiting the vehicle, the HVAC will continue to run without AC enabled for a few minutes? When I leave and park my car in auto and walk away, the car seems to be off and I don't hear any of the HVAC fans running.

There is a delay before it happens. If your car is parked in you home garage, check every few minutes, you will eventually hear the fans turn back on. The idea is to do it while the driver is away from the vehicle so they don't hear a noise and question why there is a noise or why it isn't shutting off.

2) run in manual mode, but turn off AC mode five minutes before arriving home. Presumably turning off AC but allowing the fan to run will achieve the same thing as running it in auto mode, and I prefer the manual adjustments I can get with manual mode.

Thanks for the insights!

You can try doing that, but there is a theory about manual recirculate that seems to trigger the smell (plus manual mode may not be as efficient as Auto). Note to do "fan only" the only reliable way is to put temps to "LO" with AC off. If you set a temp, there is a possibility heat is run depending on the temperature in the cabin.

 

[QtownTaxiGreg]

I'll share my experience with the dreaded A/C smell and how I think I've fixed it. I've done the HVAC settings and blasting the heat for an hour thing but the smell would always come back.

I've had my 2018 LRM3 almost 6 years and I think I've replaced the filters and used the foam cleaner 5 times from the awful stink. Last year I watched a YouTube video of a guy doing some testing on what exactly is happening and his conclusion was the bottom of the stock filter is wicking water that might collect at the bottom of the tray (even if it is draining properly). He would use a moisture meter on the bottom of the filter and you could see the filter was damp after most of the tests. Last time I ordered filters I went with aftermarket ones that have a plastic shell around the sides instead of the stock ones that are just unprotected filter paper. It's been almost exactly a year and I have had ZERO smell. Usually I couldn't make it a month into a rainy spring season without the smell coming back but here we are in June and it's been fine.

Which filter is this? I could pull mine out and paint with the liquid tape.

 

[timothydog76]

Which filter is this? I could pull mine out and paint with the liquid tape.

I bought the filter package from the T Sportsline website:
And now I'm looking at it its actually not plastic around the whole outside but there is some padding but there seems to be a barrier between that and the filter material. Whatever it is it seems to be working great.

Tesla Model 3 / Y HEPA Cabin Air Filter & Kool-It Evaporator Cleaner Kit

T Sportline engineers have created the perfect air filter replacement and evaporator cleaning kit for the Tesla Model 3 / Y. Our kit starts with the DIY-friendly Kool-It Evaporator cleaner, which is used to clean your air conditioning (evaporator) heat exchanger. The notorious 'dirty laundry'...

tsportline.com

 

[QtownTaxiGreg]

I bought the filter package from the T Sportsline website:
And now I'm looking at it its actually not plastic around the whole outside but there is some padding but there seems to be a barrier between that and the filter material. Whatever it is it seems to be working great.

Tesla Model 3 / Y HEPA Cabin Air Filter & Kool-It Evaporator Cleaner Kit

T Sportline engineers have created the perfect air filter replacement and evaporator cleaning kit for the Tesla Model 3 / Y. Our kit starts with the DIY-friendly Kool-It Evaporator cleaner, which is used to clean your air conditioning (evaporator) heat exchanger. The notorious 'dirty laundry'...

tsportline.com

Seems to be a stuck on plastic frame support. I am picking the filter medium has been antifungal treated. But I like your gumboot scenario anyway.

 

[QtownTaxiGreg]

See the other thread on water entering the passenger side via the A/C air intake? I think that may be the source rather than any mystery condensation collecting under the filter.

 

[el-guapin]

So, what's the best Mode /Setting?!

 

[QtownTaxiGreg]

Water entering into Passenger footwell from under glovebox, with fix

Left a Model Y out in the rain overnight, and next day after accelerating, water came dripping into passenger seat well from under the glovebox. Found lots of threads talking about it, but no solution being clarified, or having service center fix it without explanation, etc. Good youtube video...

teslamotorsclub.com

Colour me suspicious all mouldy filters happen this way.

 

[stopcrazypp]

Water entering into Passenger footwell from under glovebox, with fix

Left a Model Y out in the rain overnight, and next day after accelerating, water came dripping into passenger seat well from under the glovebox. Found lots of threads talking about it, but no solution being clarified, or having service center fix it without explanation, etc. Good youtube video...

teslamotorsclub.com

Colour me suspicious all mouldy filters happen this way.

Unlikely. There are some rare reports of flooding in the passenger footwell, but that's far from the common case. When water gets into the "proper" area, all it does is drain right back down the condensate drain to the outside. It shouldn't reach the footwell.

I can't find it right now, but I remember there was a diagram that shows some cars that didn't have the vent installed properly and water can get into a gap which allows it to then reach the passenger footwell.

 

[QtownTaxiGreg]

. When water gets into the "proper" area, all it does is drain right back down the condensate drain to the outside. It shouldn't reach the footwell

Where is the proper area in relation to the filters?

 

[stopcrazypp]

Where is the proper area in relation to the filters?

I can't find the diagram right now, I remember someone posted some owners that described the flooding problem in detail and they had a handy diagram that shows how the water was supposed to drain and the cars with flooding problems, there was a gap along the way that allowed the water to drain into the passenger footwell.

Edit, sorry remembered incorrectly. It was Korean and Model Y (not sure if it applies to Model 3). Here is the handy diagram:

Model Y water leak

In that case, not only may water drain into the passenger footwell (which would soak the carpet), it would also soak the sound proofing insulation inside the console. This could be a breeding ground for mold and cause a moldy smell, completely unrelated to the HVAC system and filters (all the HVAC system may involve is provide the airflow to spread the smell).

 

[QtownTaxiGreg]

I can't find the diagram right now, I remember someone posted some owners that described the flooding problem in detail and they had a handy diagram that shows how the water was supposed to drain and the cars with flooding problems, there was a gap along the way that allowed the water to drain into the passenger footwell.

Edit, sorry remembered incorrectly. It was Korean and Model Y (not sure if it applies to Model 3). Here is the handy diagram:

Model Y water leak

In that case, not only may water drain into the passenger footwell (which would soak the carpet), it would also soak the sound proofing insulation inside the console. This could be a breeding ground for mold and cause a moldy smell, completely unrelated to the HVAC system and filters (all the HVAC system may involve is provide the airflow to spread the smell).

So, leaks all over the place.

My main concern is the apparent ubiquity of the mouldy filter syndrome. Mould and me don't get along.

Tank the filters, seal the unsealed scuttle and hope like hell the cabin floor junction is ok.

 

[timothydog76]

So, leaks all over the place.

My main concern is the apparent ubiquity of the mouldy filter syndrome. Mould and me don't get along.

Tank the filters, seal the unsealed scuttle and hope like hell the cabin floor junction is ok.

These are the videos I was talking about. If you haven't seen these they are a great investigation into the problem.

 

[icy1007]

Newer Model 3s don’t really have this issue thankfully.

 

[Kilotango74]

Newer Model 3s don’t really have this issue thankfully.

They don’t? Or you have not experienced it yet……Unless they redesigned the air intake and how the filter sits it will still be a problem in the right conditions.

 

[stopcrazypp]

They don’t? Or you have not experienced it yet……Unless they redesigned the air intake and how the filter sits it will still be a problem in the right conditions.

AFAIK, there was no significant change for the 2021+ refresh in the hardware. The major change is by then the software update that dries the evaporator had been out for a while and that did reduce many cases.

I looked at the Highland service manual and the filter system is pretty much the same as the old one.
| Tesla
Old:
Model 3 Service Manual | Tesla

 

[Flipcyde]

Tesla Model 3/Y Cabin Air Filter Clip (to prevent odors)

I've been doing the whole cleaner and change filter routine twice a year because of the smell.

I put on the clip last fall and so far no smell.