Stuck heat/AC fan buttons?

[MustMakeAmends]

Yesterday, it turned cold here, quick. And for the first time, the climate control's auto/low/high buttons on my 300E's were uncooperative. I couldn't change it from low to auto without punching in each one a few times. Is this related to the cold, or my impatience ("heat Now, dammit!"), or are the switches or vacuum activators going down?

The fan buttons didn't feel sticky or gummed up, it's that they didn't want to "catch" when pushed. All 3 of them, which I never noticed before.

Update: Today, w/the fan buttons back to normal -I'm wondering if the fan buttonsare affected by cold if dirty?- now I'm only getting a small amount of air flow to the floor, even on high fan, at any Htg/cooling setting. Most air seems to be going to dash registers and windshield. Related?