Ventilation Leak, 90 MX6

[graceoverall]

I've got this 90 MX6 that, in the winter, gets EXTREMELY foggy inside. When I tore apart the dash on the passengers side in search of what might be causing my carpet to be wet I thought it might be a leak in the floorboard. As it turns out, there was about 3-4 cups worth of water stored up in the ventilation duct just past the heater fan but before the core. When I switched it from "recirculate" to "fresh" air it gushed forth water everywhere. I thought, "well there it is," but as I tore open my debris guard (at the base of the windshield), removed the window wipers, and dug in I noticed a significant lip where the fresh air funneled in. I poured lots of water down that trap to make sure it wasn't leaking and sure enough it wasn't. It would take a LOT of sloshing around for any significant amount of water to make it over the lip down into the ventilation system. The drain guard was free of debris too. Also, I don't have A/C so that's not it. I'm out of ideas. Anyone got any tips on how I could troubleshoot this further? I'm sure I'm not the only one suffering from ridiculous amounts of condensation on the interior of the windshield anytime it's damp and cold outside (which in Oregon is almost a constant). It makes it EXTREMELY dangerous to drive, especially in the rain and at night. Any suggestions would be greatly appreciated. Thank you.

Matthew
Confused and concerned (bang)

 

[xelderx]

Just making sure here before we move on to the next step...you're pretty sure it's not a leaking problem, but a condensation problem...right?

 

[graceoverall]

Condensation vs. Leaking

Yes. I am sure.

I suppose it's possible that there could be condensation as well, but I don't think that's the major issue. You might give me more of an idea what you're implying in either situation so I could better answer your question. I really appreciate your help and response. Thank you!

 

[xelderx]

Yes. I am sure.

I suppose it's possible that there could be condensation as well, but I don't think that's the major issue. You might give me more of an idea what you're implying in either situation so I could better answer your question. I really appreciate your help and response. Thank you!

I was thinking that if it's just simple condensation building up over an extended period of time in one spot you could drill a small hole to let the moisture drain out instead of build up. It sounds like it's something else though, since a slow build up of condensation would typically evaporate on it's own.

 

[randyscycle]

I'd get a friend to help by running a hose all around the outside while you are inside watching what happens. Condensation generally won't build up that much water. A heater core would leave coolant in the ductwork. If this problem cropped up very recently, I'd look at any other factors as well. Have you had a windshield replaced? Any trim work done near the front of the cowl? If there is enough water to fill part of the heater box, it would have to be a pretty significant leak and I'd think pretty obvious as well. Keep looking and I am sure you'll find your source.

 

[graceoverall]

Not condensation...

I haven't had any work done on my car (windshield, trim, or otherwise) but this problem did arise last winter as well. I also doubt very much that it's condensation but there's a funny thing that seems to be happening. I've left the ductwork exposed and carpet pulled up for the last few days while I observe it, and I've also left the heating system constently switched to the "fresh air" mode in order to leave the system exposed to the outside air. It's too soon to tell but so far I haven't noticed any dripping. I'm wondering if it's a bad seal in the FLAP that directs air from the outside or inside and possibly it's letting moisture in but not out. That's the only possible source of condensation I've been able to discover so far.

As far as the heater core is concerned, I haven't replaced it but it looks to be in fine shape other than a little minor rust. I don't smell any funny burning-antifreeze smells either so I don't think it's leaking.

I wonder if the leak could somehow be coming through the firewall? I'm running out of ideas as to what possible connections there could be that would allow water to get directly into the ductwork? I'll have a friend try the hole thing and see if that yields any progress, though I doubt it will because I pretty much did that already.

Thank you kindly for your help. I really appreciate your time.