Battery drained completely and water on rear floor

RAYXOXO

MEMBER
1999 MERCEDES BENZ C230
4 CYL
2WD
AUTOMATIC
93,300 MILES

My battery drained completely, and I had it replaced.

Since then, my a/c-heater fan quit working and the driver's side window works only on holding down the button. All other windows work fine.

When it rains the passenger's side back floor is getting very wet and only in that area.

I tried checking the sky light and the trunk, but they look good.

I have no idea as to where the water is coming from but the radiator water is good so it doesn't seem to be coming from the heater.

A mechanic friend who doesn't work on Mercedes said that he couldn't find the leak either, but he was sure that a Mercedes tech would have no problem finding the faulty leak.

TIA
Ray

3 Replies

GFIMOTORCARS

MECHANIC
673 POSTS

The water you are speaking of sounds like a sunroof drain leak. At the rear and front of your sunroof assembly there are drains which channel water through the interior side pillars to the ground. If one of these becomes cracked or falls off the fitting it is attached to you will see interior floor leaks. I would say you are probably looking at a right rear drain tube that is the problem. This is a big job to fix and requires extensive disassembly of the interior. The headliner and all a, b, and c pillar trim will have to be removed. The parts cost will be minimal as the tube is not expensive, but labor is pretty high on these repairs because of the extensive disassembly. As for your window, hold the window switch in position 1 up(position 2 is the auto up function) and bring the window all the way up. Now hold the switch in this position for 10 seconds. Now lower the window fully and hold for 10 secs. The window should now be re-normalized. As for your fan not working, it is probably unrelated and you may just need a blower motor regulator to fix this.

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Thursday, January 1st, 2009 AT 2:33 PM

NOBODY123

MEMBER
1 POST

I stumbled on this question while looking for other stuff. I've been an MB main dealer tech for 15+ years and I'm pretty sure I know the cause. The air intake for the heater under the left bonnet vent has a blocked drain. This is very common for this model and should be cleaned out during annual service. This gradually fills up with water to the point where it spills over the lip into the car. This soaks the heater blower motor and/ or resistor, shorting them out. The water ends up under your passenger side carpet. If left unchecked, this can cause corrosion to the can-bus connectors there, causing you major electrical malfunctions. Appreciate this reply is like 12 years after original post, but it may help others. Regarding the lack of one touch driver's window operation, it probably just wants re-normalizing after the battery disconnect. Drive it all the way down, then all the way back up, keeping the window switch operated for several seconds after the window reaches fully up.

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Thursday, October 21st, 2021 AT 10:51 AM