I assume your referring to the ACC as the push button unit. This is most like due to broken contacts which can be easily resoldered. Don't try and figure out which ones, just resolder them all according to the DIY here :
http://diymbrepair.com/
The climate control has 3 main units. The push button unit, the climate control unit which is a silver box with an analog circuit inside and 16 or so pins, and the blower regulator which gets it's signal from the CCU and the toaster (resistors located on passenger side of engine compartment).
On that are the ancillary units that do the real work, the vacuum pods, blower motor which get their signals from the aforementioned units.
Good luck