Mode door actuator?

I have a 2007 Limited 4Runner. I'm trying to figure out which HVAC actuator goes to which function. My problem is that the air is stuck in defrost mode. From what I gather on other threads, there's three actuators, but there's no explanation as to which ones do what. I've found out that there's two on the passenger side (an upper and a lower) and one on the driver side. A part number would also be greatly appreciated in case taking the actuator apart and cleaning it doesn't fix it. I've found all three actuators on various parts sites but they all have no description and they're all named something vague like "HVAC actuator", so it's hard to tell which one to order.