I had water (or something else odor-free) drip on my right foot while driving last summer. The AC was on at the time. I later read about the heater core leaking coolant into the driver side footwell and figured that this was going to be a real PITA to replace.

I hadn't done anything about it and then last week a mechanic showed me something strange while he had my 190e car up on a lift. He pointed out the AC drain and told me that he had never seen one with a rubber hose wedged into it. Picture a piece of vacuum hose wedged sideways into a flattened plastic drain.

Thinking back to last summer, I realized that the water wasn't hot coolant, but COLD (AC?) water!

Is it possible for a plugged AC drain to overflow back into the cabin? If not, what could explain the cold water?

Yes it is possible. Make sure the drain is not blocked and routed properly. If not, then the condensation has no where else to go.

__________________
Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record

As far as I know the flatten plastic drains are not the A/C evaporator drain tubes. The drain tubes are foam and have a wire coiled up inside them, I guess so they keep their shape. See photo below.

You say the fluid was dripping on your right shoe. So I presume then the fluid was dripping from directly above you right foot. If that is the case I don't think it was from the bottom of the evap box where the drain tube are located. The drain tubes are on the bottom of the evap box and exit the vehicle through the tunnel.

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About the only place fluid could leak that could drip down on your right shoe from above would be from a leak in the aluminum tube circled in red which goes to the heater core in the photo or from a leak at the rubber hose that attaches to the tube which is located in the engine compartment near where it goes thru the firewall.

The red arrow at the bottom points to one of the places where the foam hose attaches.

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Depending on the humidity and the capability of the AC, I have seen the ductwork condense water within itself and even on the outside. This often is the cause of water falling on ones feet.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Thanks for the detailed responses. I'm going to investigate the areas suggested ASAP.

I'll let you know if I find anything.