What with all this wet weather combined with dead blossom falling off the trees, now would be an excellent opportunity to check the drain hole isn't blocked near the a/c intake. I didn't on my '99 CLK and have just spent the entire afternoon trying to dry entirely flooded n/s front and rear footwells!! I ripped that useless rubber "valve" off too as all that appears to have done is trap twigs and leaves allowing it to overflow into the a/c intake. Well done MB!!!