as always, check fuses first.
then scan this car, it will show, mode motor errors. huh?
those are damper. in the heater box.
there are 2 fail points (besides wires)
the control is bad,
or the damper is failing.
The FSM covers this 100%
or at alldata.com
what tech does is makes sure the control sends the signal
the damper (there are 3 types used on all cars)
if its damper motor , the FSM shows the damper tests.
which are unique to Toyota. and a spec, year, 2006.
the mode damper is failing.
the only question is why,
the answer is simple tests. detailed in all FSM of all cars made.
here ill look your up to see which of the 3 type class it is.
your car has a ACC brain, a/c controller, this controller runs the show.
it gets your inputs from the defrost switch and then sends signals
to the mode motor.
FSM quote
Air Vent Mode Control Servo Motor ControlWhen the mode select SW is pushed, the ECU in the A/C control assembly activates the air vent mode control servo motor.
The servo motor rotates to the position (FACE, BI-LEVEL, FOOT, FOOT/DEF, DEF) selected by using the mode select SW,
and moves the damper.
In auto mode, A/C control assembly controls the damper to move to the best position for the conditions without operating the
mode select SW.
I SAY SCAN iT
using any scan tool that suports full Toyota. full scans including
extended factory codes..
i say buy one.
here is one.
http://www.amazon.com/gp/product/B001QIUGVI/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1
owning complex cars, and DIY, you need a real scan tool
or just guess.