[Drmaddox13]

So, I've been scouring through here and other places for days and I haven't been able to find an answer. So, here we are. The other day I noticed a mildew smell in my 2017 Focus ST3. I eventually pulled up the front passenger side carpet and discovered the floor pan was very wet and the sound insulation was saturated. The confusing part, the carpet is not wet at all. It is only in the very center of the floor pan, nothing up the firewall or sides. I dried it well over two days with a fan, the water returned. I have checked all of my drains and they all are clear. Any ideas?

 

[StanE]

Sunroof drain or maybe the hvac condenser drain blocked.....?

 

[ddfred]

So, I've been scouring through here and other places for days and I haven't been able to find an answer. So, here we are. The other day I noticed a mildew smell in my 2017 Focus ST3. I eventually pulled up the front passenger side carpet and discovered the floor pan was very wet and the sound insulation was saturated. The confusing part, the carpet is not wet at all. It is only in the very center of the floor pan, nothing up the firewall or sides. I dried it well over two days with a fan, the water returned. I have checked all of my drains and they all are clear. Any ideas?

AC condensation drain runs down from the passenger side of the console near the dash; if it comes off it will wet the passenger floor and if clogged water will eventually find a way out into the interior . The AC runs when the defrost is on. If you have the sun roof, sometimes the drain hose will plug and it will overflow into the inside of the car. Also, some have had the AC case crack and leak into the interior.

 

[MtnMan]

I checked my sunroof drains shortly after I got my ST (first sunroof), they were fine.

Later got the mildew smell. The hvac line was folded over under carpet. Poured water through to be sure not clogged and it came out on ground, so hooked back up.

But it doesn't make much of a puddle running ac. Not smelling, but I've been reluctant to check it since it took about a week to dry out in the summer, with a fan and heat from a boot dryer.
Be aware it will run under the front seat into back passenger footwell too.

There is a rope gasket around the bigger cover near where air filter goes I haven't checked yet.

There better not be a cracked case

 

[Mzdrati]

I read a thread on these forums once where a member had the same symptoms. It turned out that the leak was actually coming from the rear door. There was an irregularity in the way the door seal was positioned, and it basically funneled water into the area under the front seat, which migrated into the lower padding and floor pan.

 

[Drmaddox13]

Update: I located my leak. After running through all of the above floor options to no avail (flushing drains, AC, weather stripping, windshield, etc) I placed tissue paper under the carpet lining the entire floor pan. I went through an automatic car wash, and finally located it. Somewhere in a gasket around one of the floor plugs is a hole. My solution, I put my car up on a lift and thoroughly cleaned and stipped the underside of the floor pan. I then primed, and used a heavy duty rubberized sealant. On the inside (until I'm sure I sealed it off) I lined the floor with heavy duty clear plastic. Attached are some pictures of my leak location, the plastic sheet, and my car so if yall see my out and about you can stop me and say howdy. Hopefully this saves someone else the trouble.

 

[MtnMan]

Thanks so much for reporting back with pics!

I'll check that area in mine when I go under the front again.

I am happy to report I slid the front seat all the way up, pulled rear duct off, and foam under back half of carpet is still dry

 

[Mzdrati]

This is interesting. Water was coming in from the bottom of the car (through or around a unibody drain plug)? Seems as though the volume of water would be minimal while driving in the rain, but apparently I am wrong. Water intrusion would be non-existent when parked outside overnight in the rain, since the water has no way of getting under and then up into the car.

If this can happen to your beautiful example- it can happen to anyone's. Congratulations on finding the source of the problem!

 

[Drmaddox13]

This is interesting. Water was coming in from the bottom of the car (through or around a unibody drain plug)? Seems as though the volume of water would be minimal while driving in the rain, but apparently I am wrong. Water intrusion would be non-existent when parked outside overnight in the rain, since the water has no way of getting under and then up into the car.

If this can happen to your beautiful example- it can happen to anyone's. Congratulations on finding the source of the problem!

The volume of water is definitely small, but over time as it continued to saturate the insulation i think it finally started pooling. Thanks for your input and support!
Also, I dont know if this is allowed, but if any of yall have Instagram and want to talk shop mine is drmaddox13

 

[TurboGT]

The floor plugs are just plastic with a thin silicone gasket to seal against the top side of the floor. Im sure the pressurized underbody wash is what found the leak. I'd say your repair should do the trick.

Pic of the plug for reference.