I've got an Impreza with the three dial heater controls. Has anyone ever seen the little gear behind the Temp control break. Mine did. Snapped right off where the cable to the heater box goes into it. I got the part...$12 for a little plastic gear. I tried to put it in about a month ago but gave up. It's a real pain (who has hands that small??) to get the climate control unit out of there...not enough room to work. I've just been adjusting the temp manually by turning the little wheel down on the heater box. Suppose I'll try again when I feel like it.

 

Anyway....anyone ever have this happen before? I thought it was kind of weird. Maybe temperature changes making the plastic more fragile? I dunno.

The gears get brittle with time, but i would replace the cable too. It can be that the cable was binding (im assuming there is one) and that caused the gear to break.

 

nipper

Update because I've had exact same problem. The part in question is no. 14 in the diagram,

and the dealer had it in stock. Must be somewhat common. To work on the control unit, you need

to disconnect the cables at the heater box, which gives you wiggling room to unplug the wiring,

and then you can take it out and fix it "on the bench".

Another thread brought back from the dead....

 

But thanks anyway. I was wondering why I couldn't get the bloody thing out. I've been living with it ever since it broke. It's really not that big of a deal, but it would be nice to have with the temperature changing. Reaching down to the heater box every morning to switch to heat for defrost isn't fun.