Heater stuck on "hot"?

[w44ne g]

I've just rang about a 172. Sounds like a nice car but the heater is stuck on the hot setting (it's got climate control). The seller is saying its something to do with a motorised flap in the system but I'm guessing if it's an easy fix, he would have repaired this.

Is it a known issue and a big problem to sort out?

 

[Addicted]

Sounds like resistor pack?

 

[Typhoon]

I'd say its the variable speed sensor.

 

[182_Adam]

Sounds like resistor pack?

this... common fault