Heat is on all the time

I have a 2001 Tacoma that the heat will not turn off. I checked some obvious items that could cause this. The heater control valve and cable are working ok. I did find that the Air Mix
Control Servo Motor is not working when the Hot/Cold temperature knob is adjusted from
hot to cold. Anyone know where I can find the diagnostic procedures to test the operation
of the heater control assembly to the air mix control servo motor??

 

Instructions from the 2003 FSM how to test the servo motor in this thread. Pretty easy to pull (3 screws) and test. I did it. Replaced it with one from a part out almost 5 years ago now and still working.

https://www.tacomaworld.com/threads/let-there-be-heat-please.580876/page-2#post-19422836

 

Thanks for the info. I will test the servo motor.