Front A/C is blowing hot while the rear A/C is blowing cold?

So, this car has dual climate control, could you tell if both sides were warm or just the one side? If it was just the driver's side here is the air blend door actuator for the driver's side in the images below. If it were both sides, I would try the mode actuator, to be sure this is the problem when the actuator is removed you can work the door by hand to see if it changes and fixes the problem. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem.

Sounds good, the pop you heard could be the actuator getting itself unstuck or working through an obstruction in the vent.