Leak from heater box in the rain

[98legacy22stick]

Hey, Wondering if I can get some troubleshooting tips for this strange problem.

Whenever it rains, water is leaking into the car from what looks like the heater box and into/under the passenger side front carpet. More specifically, it looks like water is coming out of the gap in the heater box where the heater core section connects with the evaporator section. It is a relatively small amount, but enough to leave a puddle. I've already tested to ensure that water does not leak when the A/C is on. Anyone have any ideas on what to look for? Are there any body drain lines in that area? That might cause this?

The only other clue I have is that on rainy days, when I turn on the blower motor, I hear a small amount of water churning around in there, and when I'm driving in the rain with the blower motor on, I will occasionally hear a drop of water hit the blower. I know the climate control is drawing in outside air, is there some kind of air water separator, valve, or drain line in the air inlet that might be clogged?

Thanks for any suggestions you have.

[Legacy777]

Do you have a sunroof?

Have you verified the drain hose on the AC system is not plugged?

I'd probably suggest removing the blower motor and looking in the evaporator box to see if you have standing water in there and also look up at the air inlet to see if you can see any oddities from the ducting going to the cowel under the windowshield wipers.

[98legacy22stick]

Thanks for the reply. I don't have a sun roof. I removed the AC drain hose, verified that it was not clogged, then reinstalled, ensuring that it was not pinched during installation. I'll give removing the blower motor a shot and see what happens.

[BSOD2600]

Unless the heater box somehow got dislodged from the evap section.... otherwise, I guess the seals on the evap box have gone bad. I didn't think it was normal for water to even get in the HVAC system, so sounds like you've got bigger issues at hand and are just chasing a symptom.

[Legacy777]

You're going to have water in evaporator box due to the water vapor in the air condensing on the evaporator.

[BSOD2600]

You're going to have water in evaporator box due to the water vapor in the air condensing on the evaporator.

Agreed and hence the drain tube.

But water shouldn't be coming it from the top though normally, right?

[Legacy777]

What do you mean the top?

Guess I don't understand the question.

[BSOD2600]

The OP stated that water is coming in when it rains and leaks onto the floor via the evap/heatercore. Obviously that's not normal. It shouldn't be making its way into the car via the outside air vent (or where ever else it's leaking in)... which is at the top of the dash/HVAC system

[Legacy777]

I guess he needs to verify whether the water is coming in through the HVAC system.....or possibly a leaky windshield seal.

[vrg3]

BSOD2600 - I thought that was normal. Doesn't rainwater fall through the cowl into the evaporator box?

[98legacy22stick]

I still haven't had a chance to really investigate this, but from having replace my expansion valve while working on the A/C system, I can see that the gap between the heater section and condensor section is not designed to be water tight(correct me if i'm wrong). Theres just foam pieces between the 2 sections. Looks like all condensation drips from the condensor into a depression in that section, and then out the drain tube.

I also noticed that the inlet to the blower motor is covered by the cowel in such a way that water will not in an ideal situation fall directly into it. Water will collect in the section of the body under the cowl, and then drain out through holes, avoiding the blower inlet. I saw that a section of cowl right above the blower motor inlet was separating from the windshield. I'm thinking this might be a potential leak path directly into the system, especially since the problem does not occur every time it rains. I will put some silicone sealant in that area to bridge the gap between the cowl and windshield and do a hose test to see if the problem goes away.

[98legacy22stick]

Alright, slow progress. Still been too lazy to take a close look at the problem but after a night of heavy rain, I got in the car, turned on the blower motor, and observed water leaking out of the connection between the blower motor and fresh air supply tube. So I will eventually remove the cowl and figure out what is plugged or not placed correctly.

Just updating the thread so that there is some kind of conclusion included.

[ericem]

i remember a long time ago my 93 legacy had a weird issue. When we went through the car wash water and soap would spray out of the vents when the fan was on. After going through a car wash a few times cleared out what ever was clogged. I am guess the area where is sucks in air has drain holes.

[98legacy22stick]

Problem Solved:

Finally took the time to look at this, as the last weekend of rain pushed me over the edge. I took off the windshield wipers and cowl, and then removed the blower motor so I could see both sides of the air inlet.

Long story short, one of the holes in the car for the clips that holdes the cowl in place is right above the inlet for the blower motor. When I had replaced the windshield last year, that clip had broken and I replaced it with a similar, but not identical clip. Since the new clip was slightly smaller than the hole, water was leaking underneath the windshield cowl and dripping right onto the blower motor. This theory was proved by a water test, as well as finding the broken part of the clip in the blower when I removed it. My fix was to swap the clip with with the one on the other side of the cowl which was an OEM clip and apply a generous amount of sealant around the hole to ensure that water will not get past it.