My wife has a 03 Explorer. When she goes to switch it to heat, you can hear the door like thing under the dash trying to close, but no heat. I took the panel of yesterday and saw the part trying to close, so I reached up in there and pulled it down and it close, then it started to blow hot air. Is there something going out that I need to replace? On the other side is a small motor and it sounds like the little plastic gear on it is stripped. Should I look at this first? And how do you get it out of there? It's in a very tight place.

 

Do a search for blend door actuator, blend motor. Pretty common problem with a lot of good writeups on how to fix this problem. May require dash removal which is a PIA but worth your time when you see what the dealer charges.

Tennfan