Q&A

i just replaced the blend door because it was stuck on a/c. the a/c worked great, but now it's getting colder out i went and bought the blend door and replaced it. after i hook it up and connected everything, i turned on my explorer to check to see if everything is work the way it should. I put it on heat it works great now it down switch to a/c. what would cause this? I did reset the computer and that didn't fix the problem. Please Help