looking for water problem, created a new one I think.
 

I posted a reply, not a new topic. Still getting used to things with this forum and posting. While attempting to locate the water problem, I may have created a new one?

Just to make things clearer, my car is a 1981 280SL euro model 107 was in dry winter storage, under cover. It was run a few times during the cold, in order for me to get heat I turn the fan switch and the def/light turns on. I assume the AC unit then turns on even with the need for heat?

After I discovered the water under the floor, and posted my problem I took the helpful advise, looked for the drain from the underside of the dash.I found a rubber plug, about 1" in diameter in the middle of the floor under the black floor insulation on the drivers side flooring.

I can't locate the water source yet. I tried to remove this plug in the middle of the flooring to get a look inside, and the plug fell into the flooring which is about 2 " deep. I tried, but with no success to get the plug back out it just rolled out of reach. I ran the car, did not run the AC/DEF, and the floor remained dry. I hope I can replace the plug, does anyone know what that plug is for. While driving, I put my hand over the hole, felt warm air out of it. Do I need to be concerned ?

I'll continue to look further into the water issue this weekend. I think it must be AC related.

Thanks for the advise, I think I'm on the right track. I'll edit my profile so that my car, model, and year is posted.

dcoisson

I have had several cars with mysterious water leaks. More times than not they ended up being front or rear window gaskets. I know, I also at first didn't beleive it. I spent time pulling out under dash areas, looking for blocked drain holes, finding open areas etc etc and replacing trunk gaskets etc.

Someone finally asked if the window gaskets were good. My reply was "Well they are not cracked or torn" Their reply was a simply test: Where the rubber meets the body, when the rubber edge of the gasket is lifted up, does it snap back? Mine didn't. They would kind of fall back. I replaced the gaskets and no more water problems.

Worth a try.

My 2 cents