Hot or Cold at random -2004 Toyota Highlander

My 2004 Highlander air conditioning air shifts from cold to hot at random (well maybe more often after going over a small bump). If I rotate the temperature knob from cold to warm and back, it goes back to feeding cold air. it happens when air conditioner is off and the fan is feeding outside air as well. When I asked my favorite repair shop about it their eyes rolled back - I don’t think they wanted to tackle it. Is this a mechanical problem or electrical problem? Anyone have any ideas how to tackle fixing it? Should I take it to the dealer (ouch)?

If your “favorite repair” shop doesn’t want to deal with your problem, I would suggest the dealer or
an independent shop which specializes in Toyota

Try pulling the temperature knob off and see if the nut behind it is loose. This fixed the problem for me a few years ago.