how do i fix the temperature control for the heater in my 96 gmc sierra pickup?

[Douglas]

all controls work but the hot-cold dial.I only get heat no matter what i turn the knob to

 

[charlie]

Need more information, is the blower working? All speeds? Or are you talking about the hot/cold settings...?

 

[Trey]

Buy a new control unit..If that isn't the problem it is something else such as a bad heater core.