Blend door or switch? Heat won't go off.

I just got a new daily driver (98 S10) and the heat stays on. The blower control works fine as well as the control that turns on the ac and directs where to blow the air. The problem is the knob that turns the air from heat to cool (blue to red). I am trying to see if there is a common problem with the blend door actuator or the control switch itself. I am hoping it's the control switch but at the same time I don't want to waste a bunch of money replacing the climate control if it doesn't fix the problem. I've searched and searched but the only vehicle I can find that has a common problem with the blend door is Fords. I can't even find a part number or anything at all on GM Blend door actuators. Anyone else had this problem?

part number is 89018365,and its a common problem on full size trucks too

happenes alot on the older ones mine was just a cable that connects to the back of it

i think my problem may be this part too. what do you think? when i turn on my truck and the ac is on recyled air the flap closes and will click for about 10 seconds. same when i turn the truck off. it will click for a while. Its like its not sencing that its closed all the way.

my work truck does that, we just drive fast with the windows down. seriously, no joke. my boss is too much of a cheap ass to have it fixed.

Thanks for the part number. I'm going to replace the switch first since it's cheaper and easier to change.