I have a 2013 impala ltz. I believe an actulator is going out, but I just want to ensure I know which one. Whenever you open a door it starts to tick like a mad man. Also, whenever you switch vents it ticks as well, switching to hot/cold makes it tick, and the passenger side ac/heat doesn't always switch. I'll have it max on heat and its ice cold, so I have to go to cold then back to heat for it to switch. Inlet actuator or the blend? Easy to replace?
You have a lot of clicking going on ! You get it when you switch vents (mode actuator) and you get it when you move the hot/cold knobs (blend actuators).
I don't know all the details of the HVAC software, but it may be that, when the processor detects a change in any setting, that triggers it to check flags, and, if it sees a flag set that it has lost one actuator, the bad one, it may go try and re-calibrate that one actuator while it's also responding to the other input change.
For example, if the passenger side blend actuator is bad (and the others are good), and you make a vent setting change, while the software powers the mode actuator to select the different vent, it also tries to re-cal the bad blend actuator so you hear it clicking, and not the mode actuator.
Or, maybe you have more than one bad actuator clicking
The point is that it may be one actuator making the noise even tho you're changing settings that affect other actuators.
But I would focus on the passenger side blend actuator first since it's the one where you got cold air when it should have been hot.
As I recall, you will need to remove the trim from below the dash on the passenger side. I don't think you need to disassemble the glove box for this one, but I won't swear to that. (As I recall, that's only needed for the mode actuator and the inlet actuator.)
One test you might try is to remove the electrical connector from the passenger side blend actuator, then change some settings and see if the clicking returns. If the clicking is gone, that should confirm that actuator is the bad one.
The screws on it require a 5.5mm socket. 7/32" works well, too.