In this video shows you how to replace the rear AC temperature blend actuator and stop the clicking noise.
The clicking is coming from little plastic gears inside the actuator case. Once the teeth wear out the gears can’t grip each other and just pass by each other.
If you don’t have control of you rear temp and there is no clicking then there could be a couple things wrong: 1. The plastic teeth are totally shredded and there just nothing left, so you need to replace the actuator. OR 2. Your switch could be bad. Or 3. maybe there’s a fuse issue. or 4. maybe something else… To diagnose if its the gears in the actuator, you can remove and inspect them as I show in the video.
I hope this video helps you out and saves you some time!