Not heat temp control

[sirhC]

Was warming up outside after getting off work turned the heater temp down and no change, air
was still hot. This is a 2001 sport trac. just hit 200K miles. what do I look at??

 

[koda2000]

Blend door actuator, broken blend door, temp control switch, heater control valve. My '01 ST had no heat control when I bought it. I found the vacuum hose on the heater control valve (located under the alternator) was pulled off and the blend door actuator was bad. It's been working fine for about 4 years now.