thermostat control knob on heat & ac doesn't work on 2005 Toyota Highlander

thermostat control for ac/heat on dash turns but does not control temperature

Asked by for the 2005 Toyota Highlander
pull out the heating / ac knob. tighten the nut right behind it and that should take care of the problem.

ribbon cable behind the heater lever probably broken -
need to remove the dash cover and solder new leads.
3 more answers , 1 more comment
Check this site out. It worked for me!
Do you feel resistance as you turn the knob. I wonder if the knob itself is broken (was a problem with Honda Accords) or if the heater control valve is not opening fully. I believe the heater control valve is at the rear of the engine compartment on the firewall, it has two coolant hoses on it and a heater control cable attached to it, with the engine off get a friend to operate the heater control from hot to cold /cold to hot and see that the heater valve lever moves full distance and that the cable for some reason has not become detached. Also check the coolant level. Low engine coolant will affect heater output.
yes do what the last person said, it really worked for my loose one too!
I just repaired the 3 wires(soldered) on 2004 Highlander for the heater control panel. The heat works BUT now AC doesn't turn on. The AC selection knob turns but doesn't change any air flow. The air only blows up the windshield. I checked the ribbon cable for the know and it seems ok. Any help apprecieted.