There are vents up under the dash that open and close (or supposed to close) with vacuum. When you switch the heater control to vent it sends a vacuum signal to open the door that goes to the passenger side, and a cable does the door on the drivers side. Sometimes the cable gets rusty and sticks open a little, and this lets the rain in.
The rain is going into the vent on the cowl, and running into the heater.
You can check the vent drain tube which is located in the engine compartment, on the firewall just to the passenger side of the motor. Comes out of the firewall and points down toward the starter. It's about 1.5" in diameter black tube. Sometimes it gets clogged with mud or debris.
'87 YJ, 4.2L built and bored, 8.5" of lift, 8.8 rear, AX15/NP 231, Tom Woods drive shafts, Flat fenders, 12,000LB winch, Custom bumpers, Rattle can paint job. Never completed...
You can check the vent drain tube which is located in the engine compartment, on the firewall just to the passenger side of the motor. Comes out of the firewall and points down toward the starter. It's about 1.5" in diameter black tube. Sometimes it gets clogged with mud or debris.[/QUOTE]
Check out the thread called. "YJ Heating System Explained". I think it's a sticky. There's some really good explanations of how the hvac system works, which could help diagnose any possible leaks coming through the cowl.
Btw, i checked out my vent tube and it felt like Chicago sausage it was so full! Cleaned it and no more leaks.
I have the same problem... I pulled that hose and it was full of stuff too... but I don't think that's the problem... I end up with a lot of water in my floor boards... maybe a half a quart sometimes... and there is no rhyme or reason to which side gets wet.. sometimes driver sometimes passenger.
Last night I after drying it once again, I found a little water leaking in from the side of the body... like it's coming in from the door hinge area someplace....
what's funny is it doesn't get wet in the jeep after I wash it....
Is it leaking while parked outside? Or driving your jeep? I'm doing some wk to mine and washed the engine. I noticed water getting in at the firewall. The worst was at the fuse block and around the heater box. I'm using seam sealer and silicone around theses areas and any other part that passes thru the firewall
I just replaced my window seal because it was completely shot. It fixed most of my water problem but I still get water coming in on the passenger side although it is a lot less. I have checked the tube that comes out of the fire wall on the passenger side and it isn't clogged. I ruined my stereo and speakers becuase of the water and would like to replace those as soon as I get the water problem fixed. Any ideas??
If you have already checked hour cowl seal and its not leaking you might think about silicone along all the sheet metal seams under the windshield and the panel joints near the factory antenna and on the drivers side as well. I used a toothpick and rolled silicone into all those joints and it fixed all the dribbles into my cab. The other place water came in btw was the trac on the windshield for the soft top so I pulled that and siliconed that as well to stop leaks up high.