Checking the temp. control knob.

[jeff1998]

My 98 Eddie Bauer is stuck on hot. It will only blow hot air. I just changed the heater core and blend door. The blend door actuator does not turn with the knob. Post on the actuator is good, and the door turns with a screwdriver shoved into the hole. So how do I check the control knob without buying a new $45 actuator?? I want to make sure the controls are not bad.