Heater blend door makes ONE loud thump!

[tuik]

2003 Explorer XLT 4x4 V6, When I start engine with heat temp turned all the way up and blower motor on low (first setting) or on 2nd setting. The air is cold until I turn the blower up to the 3 or 4 position. And that's when I hear the LOUD thump. It is a one time thump and then the heat works fine after that. I can even turn the blower back down to the number 1 or number 2 setting and the heat continues to work until I turn it off or shut the engine off. Then its the same process again. So in simple form, my heat is cold until I turn up the blower and get the loud one time thump. It startles ya when it happens. What and why is this doing this? Is there a fix?

 

[rocco123]

Million differe t posts on this. On mine I removed the passenger glove box, looked thru the vent and saw the door laying down. I went for the fix where I wired the door closed and called it a day. Actuator arm on pneumatic servo for fresh air was broken.

 

[tuik]

Million different posts on a continuous noise. But not on a one thump noise, like I have. If you see more than the one post I seen on this, that didn't have a solution. Please forward to me the others? I would very much appreciate it.

 

[axeman06]

My 05 did the same thing for about a year, then no heat. Changed the blend door actuator today and all work fine again. I'm Guessing my actuator was working just enough to get the door moved and the high speed of the fan was pushing it the rest of the way.

 

[tuik]

Ok now that does make sense to me. Seems it is the fan that is blowing the door open, thus making the one time loud thump. Since yours was the same and not the continuous thumping, I believe what you did should solve my problem too. I sure hope so anyway lol. Thanks for your input