97 no heat control

Hi. My explorer is acting up. It blows out the same hot temperature no matter where i have the dial set. Does anyone know how to remedy this?

if i recall right, to control the temperature, there is a mechanical valve that controls that, maybe its not working because its loose,
are you able to set the air to cold, on not even to cold, just hot and hot.

hi thanks for the response. the knob turns but even when put on ac and all the way to cold there is no change in the temperature. where is that valve located?