I went into my dash a couple days ago to replace the driver's side actuator, but it didn't fix the problem. The first red flag was when the mfg. date on the old motor was newer than the replacement. Opened it up and everything was fine inside, no broken teeth or anything.
The next step would be to replace the passenger's side, right?
Also, are there any tips on how to diagnose problems with temp sensors? I'm having an issue where it seems the heat is either all the way on or all the way off. Eg, it'll be 36 outside and I'll set the internal temperature to 68. It comes on full heat, which is a bit excessive, so I turn it down to 63 or something, at which point it's coming in feeling closer to ambient. It's happening on the driver's side, which is why I don't think it's anything to do with the blend door, unless the passenger's side motor affects both sides of the car.