92 190E Tempmatic Problem
 

Pressing any one of the three buttons (up/down arrows) that calls for heat produces maximum heat to the windshield only -- no floor heat -- and heat stays max regardless of thumbwheel position. Also, during cooling, a lot of condensation forms on the outside of the windshield in humid weather. Willing to try a DIY inspection on this one, but would first greatly appreciate any insight that's out there. Thanks.