I'm having a similar problem up here in wet ol' Washington State. When I first got the car (3 months ago), the rainsensor feature worked perfectly and the windshield was crystal clear. I think the dealer must have put a new blade on.
But now all I get is a big smear and it's nearly impossible to see at night, besides the fact that the rainsensor wipers seem overly active.
It seems that the auto function wipes more if there is smearing on the windshield. I can't figure out how to keep the smearing off! Am I using the wrong (aka "cheap") washer fluid? What's the best way to a smear-free windshield?
2003 Hyundai Santa Fe, Silver
1999 C280 Sport, Black
1997 Ford Escort, Toreador Red