So after months of looking at forums and such trying to find where this strange sound in the dash of my 06 4runner I have found the issue. Ive read multiple topics of other t4r owners with a similar sound that have been unsucessful at finding this noise. I felt the need to post my finding as i think they might be helpful to other owners. To describe the noise it is a faint clicking boiling sound coming from behind the dash. With the vehicle running at idle making the sound remove the glove box. Look in with a flashlight toward the center of the dash behind the climate controls. There are 2 linear actuator motors that contol the mix of the airflow to the vents. Looking carefully you can see one of the white cam plates moving to the sound of the click. There are 2 ways to solve this issue. The first free way to fix it is to remove the actuator, disect it, and clean and tighten the contacts on the idler gear. The other way is to buy a new one. I found that disecting and cleaning the contacts works just fine. I also bent the contacts toward the gear so more pressure is exerted toward the gear. Hope anyone else that has this very annoying noise is as successful as me in the repair. Note: the actuator is very difficult to remove but can be done without pulling the dash.