I have a 1992 W140 body that is currently in the shop(local MB dealer) for evaporator core ,blower resisitor,and a dash push button unit.I found out that the Evap had been done in '97 by the previous owner. Is this common to be on the 3rd core? I was told by the dealer that all three of these problems are common. Cost to fix all three is 4900.00. THANK GOD FOR AN EXTENDED WARRANTY!!!