I have a CLK 230K cabriolet 2001. I discovered that water was leaking into the passenger footwell. Shortly after that the heater fan stopped working. I took it to the local garage and was told that the drain plugs in the engine compartment near the windscreen had become blocked and water had built up into where the heater fan/pollen filter were. It cost me £278. I am anxious that this doesn't happen again. Has anyone got any advice or at least instructions on how I could do the job myself in future.