Stinky HVAC (fix)

[Nc211]

Recently bought a new endoscope and used it this morning to go hunting for the EVAP coil for the AC. I've done this procedure on many cars over the years that we've owned, works every single time with no issues. Many say the stinky AC is caused by the in-cabin air filter. I disagree, partially. Yes, you have to replace a cabin air filter every now and then, definitely plays a fact. But that nasty, stinky, "gym sock" smell is actually coming from the EVAP coil itself, which sits in a dark box that sweats condensation and does get dirty with pollen and junk. The environment is perfect for mild/mildew to form, causing the stink. I remember it happening all the way back to our 1986 Acura Legend as a teenager. Thankfully on the Bronco, it is going to be extremely easy to fix and prevent, perhaps the easiest I've ever encountered thanks to common sense engineering.

If you take a flashlight and shine it into the dash vents on either side of the dash screen, behind that screen you'll see the cutout on the bottom of the hvac tubing. The EVAP coil is sitting right there, down in there. Attached is a picture from the camera this morning. It's the aluminum tray in the photo. Mine is but a year or so old, so mine isn't bad yet, no stink.

The other photo I've attached is what I have used in many cars to fix it. You can get it off Amazon, and there are other brands/versions out there too. This one comes with about a 3 foot little tube that attaches to the can. You shake up the can, feed the tube into that box area, and release the contents of the can. It goes in a liquid that quickly turns into a foam, and then reverts back to a liquid and drains out of the drain tube under the car. Given large size of this EVAP coil, two cans may be needed. The liquid goes into the fins of the coil, foams to dislodge the mold/mildew/pollen etc, and then drains it out when a liquid again. What is left is a fresh minty smell and no more stinky socks, period. I live in hot/humid 4-season Washington DC, and I usually have to do this once every 12-18 months with our cars.

NOTE: If you do this, MAKE SURE you have the hvac setting to the dash vents ON, and only! There is a flapper door on the evap box that opens, closes with the settings of defrost, feet, etc. For instance, if you have the dash and the feet set to on, the door is only open about ½ way. Same with defrost and dash. If dash isn't on, the door shuts completely. I have a video from the camera that shows the door opening / closing with the changing of the settings, but can't seem to uploaded here.

When the car is turned off, the door rests in about a ⅓ open position to allow fresh air into the evap box to help it dry out. It is important to make sure the dash vents, especially the ones on either side of the infotainment screen, are not closed off. When you close those off, you restrict the ability for fresh air to get into the box to help dry it out, and thus accelerate the return of the mold/mildew/gym socks stink....

Just passing along in case anyone needs the help. Very happy to see how easy it is for the Bronco! My wife's MB GLS is a nightmare on this, have yet to find where the coil is located (or the actual drain tube underneath the car to feed the can tub up into). Over-engineered German crap box....

Just shine a flashlight into either of the vents next to the infotainment screen, you'll see the opening behind the screen. On mine, it's easier to see and get to from the passenger side vent, the opening seems a little larger on that side (which is the side I used to take the picture with the scope).

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[23OBX2.7]

Dealer has a spray for this my Mustang had same issue....it's not a foam some kind of disinfectant to kill the spores...

 

[Lcubed]

have you run the endoscope into the under chair floor vents and checked if they're actually connected to the rest of the HVAC system?

 

[Dan-O]

I’ve used this brand as well as others, but I drill the hole in plenum between fan and evaporator and do it per instructions. I think the results would be better when used as instructed as the foam makes contact with the dirtiest part first and gets blown through the fins. But your way is probably a bit easier just not sure if it’s quite as effective.

 

[Nc211]

I’ve used this brand as well as others, but I drill the hole in plenum between fan and evaporator and do it per instructions. I think the results would be better when used as instructed as the foam makes contact with the dirtiest part first and gets blown through the fins. But your way is probably a bit easier just not sure if it’s quite as effective.

Think mine is the shady-tree way for sure! The box suggests running up the drain tube as well. I’ve not needed to that though in the past. I can’t complain about the results. We’ve got an 11 year old VW Tiquan as well, which stunk like hell last year (bought for my son’s 1st car). It took two cans through the center stack vent before the drainage underneath stopped looking like a Hazmat clean up. Worked though, still smells fresh and new a year.

I was sort of hoping the Bronco was needing the cleaner now, since I can see the results now with the new camera. $50 well spent…

https://a.co/d/9poE2Rx

 

[MiSa09]

I’m going to try this to fix our musty smell in my wife’s 2024 Bronco. I also wonder if the A/C condensation drain is plugged. I tried locating it to clean but was unable to find the hose or port. Does anyone know where the drain is? I’ve searched the internet and have not found anyone that gives a good description with pictures.

Thanks

 

[Nc211]

I’m going to try this to fix our musty smell in my wife’s 2024 Bronco. I also wonder if the A/C condensation drain is plugged. I tried locating it to clean but was unable to find the hose or port. Does anyone know where the drain is? I’ve searched the internet and have not found anyone that gives a good description with pictures.

Thanks

Not sure if engine type matters (mine is 2.7), but it’s right above the exhaust pipe coming off the engine, where the evap coil itself is located. Mine does the “sizzler” after a long drive when hot and drips rights onto the pipe. I saw it recently when doing the oil change, it’s a decent side drip tube. I would think unless if you got mud in it, it would’ve be clogged up so quickly, but could be wrong (and not sure where you live).

Don’t forget the cabin filter too on the passenger side. Mine was far dirtier than I was expecting when I I changed it for the first time a few months ago. Very easy to do.

As a side note to the mods we all do - “drift” on Amazon in teak oil scent, are awesome in these cars!

 

[SierraBronco]

I’ve started noticing a musty smell. Really glad this thread popped up. Gonna give it a shot

 

[TLO]

So to be sure, do you notice the smell while the HVAC is on only?
When I get into my 2024 HE, it has a bit of funky smell but running the HVAC clears it up.

 

[MiSa09]

Not sure if engine type matters (mine is 2.7), but it’s right above the exhaust pipe coming off the engine, where the evap coil itself is located. Mine does the “sizzler” after a long drive when hot and drips rights onto the pipe. I saw it recently when doing the oil change, it’s a decent side drip tube. I would think unless if you got mud in it, it would’ve be clogged up so quickly, but could be wrong (and not sure where you live).

Don’t forget the cabin filter too on the passenger side. Mine was far dirtier than I was expecting when I I changed it for the first time a few months ago. Very easy to do.

As a side note to the mods we all do - “drift” on Amazon in teak oil scent, are awesome in these cars!

Thank you for the quick reply! Yes ours is a 2.7L and only has just under 5,000 miles. Haven’t driven off road much so I wouldn’t think the A/C condensation drain is plugged either but it was driving me crazy not knowing the exact location. I had noticed in the dead of summer plenty of water draining from the Bronco but about September, and oddly enough around the time the smell has increased, the dripping was almost non existent. We still had some hot days in Texas so I cranked the air conditioner and drove around for awhile and came back to the garage with no water dripping. So, this is what prompted me to try to find the drain. The smell is usually worse at initial start up and when the air conditioner turns on, and also while the Bronco is off and you are just sitting in it. The smell does clear out while driving though.

 

[MiSa09]

So to be sure, do you notice the smell while the HVAC is on only?
When I get into my 2024 HE, it has a bit of funky smell but running the HVAC clears it up.

I would describe ours almost the same as this. I was sitting in her car yesterday with it off for quite a while and noticed the smell. It is faint, but there. When the car is turned on and the HVAC ramps up it initially blows the funky smell but clears after a few seconds only to be back again later when the car is off.

 

[BigBlue7]

Where do you spray the stuff? Into the passenger dash vents?

 

[Valhalla]

Mine smells like dirt inside, probably from all the dirt inside...

 

[Dan-O]

Where do you spray the stuff? Into the passenger dash vents?

As OP stated, that’s how he did it and appears to work. However, most of these have instructions to drill hole in box between fan and evaporator, turn AC on Max and insert tube with provided tip and empty contents into plenum. Then plug hole with provided plug. Here in Arizona I do it to all my vehicles about 2x a year. Here’s a picture of my chosen location on Bronco with plug. There are many different brands with different instructions and parts, so not all the same. The one Ive been using for a few years now has tube, tips that fit into drilled hole and the plugs to seal it up when done. As was mentioned here in this thread, the filter does get a musty smell as well so not a bad idea to replace it also. On a side note, OEM filter I’ve found to be best, some of the other cabin filters claim to filter more microscopic elements but have found that air flow gets really constricted with those so I’ve gone back to OEM.

 

[CalvinT]

I've used this with great success.

A friend used it to get rid of dog smell in a used car he bought.

You still need to deal with the moisture, but this will get rid of any odors and kill what's causing them.

https://www.amazon.com/dp/B00J4GHLFI?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_3

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