My 2005 highlander has the knobs that control the heating and coolinf fan, temperature and vent. The temperature control knob is randomly changing to hot when it is set on cold and visa versa when you turn the knob the opposite way and reset it then it will work for awhile before it does it again ---help

Hello, and welcome to FixYa, Please allow me to assit you.

The issue that you are having is indeed in the control assembly. Yes, it does cost over 600 dollars to replace it.

However...if you have any soldering skills, or know someone that does have soldering skills, you can fix this problem yourself.

All that is wrong with the controller is a broken wire going from the small printed ciorcuit board that the knob is located on, to the controller's main PC board. Removal of the controller, and a disassembly will show you the broken wire. Just solder the wire back to the terminal that does not have a wire on it will fix you right up, AND save you 600 dollars!!!

Thanks for choosing FixYa for advice today.

I have the same problem. I was told by my mechanic that it is the control panel for the heat/a/c. The repair cost for a new panel new was over $600

Sounds like an actuator not responding to your input.
Take the vehicle in for servicing this may involve removing the dash board to repair.