That could be it. I don't know if REST works since there's no indicator light when I press it and the lights stay on in whatever mode it's in. I've pressed it once or twice to see what happens. I have no reason to use it though.

The ACC buttons are flaky. I can't get the passenger side to AUTO from bi-level. Have to go to deforst then select AUTO to restore AUTO. Passenger side up arrow doesn't work. Recirc doesn't work either. Gets hot or cold as neccessary which is good enough for now :/

Sixto
93 300SD 3.0