That pop could be it hitting. It's common and not a problem. You should only hear it when going from max heat to max cold

 

I do believe there is a specific procedure to 'index' the stepper motor at installation...... Should be in the service manual.

 

I had it on max cold and started turning the dial and it started making that sound right away. Before it never did that, is it possible for the door inside to come off in any way? Should I make it do a full rotation and see if it stops making that noise?

 

Read the replacement procedure for the stepper motor in the service manual. (get one here.) There have been cases where the door breaks away from the axle, but, not real common.

 

I could turn it by hand to max cold to hot. When I put it make in the shaft of the door went up to is that normal. And should I make it go from max cold to max hot to see if the popping stops?

 

Turn ignition on, turn your temp control **** to the 12 O'clock position. Wait 10 seconds. Turn ignition off. Remove the blend door actuator, (the service manual would have you remove the dash for that....... not really necessary, just fun....) Make sure the blend door can travel its full sweep. (if you can turn it hard enough, you should hear it 'thump' all the way open/closed.) Put it back together... you *might* have to take the actuator apart, and re-index it, so it goes on close to the center position of the blend door, and actually aligns with its mounting holes...... It's also possible the popping noise you hear is the coupler cracked...... making funny noises when the motor is trying to move the door.....

 

Ok, when I took it out the first time the coupler wasn't cracked but I already had the system on max cold and took it out i saw that nothing was cracked turned the shaft by hand and everything was fine probably messed up when I put it back together because I had to turn the motor a little bit to get it to align with the mounting holes.