Ticking coming from under the dash

I get a ticking coming from under my dash almost like my blinker is on or a loud clock. Sometimes it come on and is on as long as the car is running and sometimes not at all. Any ideas?

Sometimes the mode and temp doors will bind causing this concern.

Also you may want to check TSB#04-08-49-015
Refers to a clicking from the cluster caused by a bad tach stepper motor