I could use some suggestions/input here. My F150's A/C seems to be senile. It doesn't set to any particular switch setting, e.g.,panel/floor when the position is selected. What it does is search for something it likes and then resides there for awhile. Sometimes, but not always, it moves to the selected position. I've replaced the control unit, so that's not the problem. I think it's the cheap ass plastic control lines Ford uses for the engine vacuum. Anyone?