heater blend door

Your car has a separate motor to control which mode you have selected (behind dash driver's side), air intake motor (behind glove box), fresh air flap control motor (middle of dash passenger side). I am wondering if something is commanding the door to shut. You need specific instructions that are not going to be in an ordinary repair manual. If you do a lot or even some of your own repairs you can subscribe to Alldata for a one year access to one model of car information that is the same information independent repair shops use. It gives you information, wiring diagrams, service bulletins and easy to navigate. I think it is less than $30 a year. http://www.alldatadiy.com/