What is the clicking sound when I turn on my heat?

Hello, it sounds like you have a temperature blending problem inside the dash as part of the climate control system. There are little motors that engage plastic doors in the plenum to move from a position of heat to a position of cold. If you have a "dual zone" system, it's possible you have one for the driver side and one for the passenger side. One or both of these motors could be malfunctioning, or the plastic door could be fractured. Either will cause the lack of desired temperature and the clicking noise. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops