What is causing a clicking noise under the dashboard

Hello, There is likely an issue with the air conditioning system, specifically electronic components which control the flow direction and temperature of air moving to the vents. The blend door or mode door actuators are tested by the control panel every time you turn on the vehicle, and if they cannot be rotated through the complete range of motion, they will continue trying. Also, you may have damage to the blower motor assembly, or there may be a loose or broken blend/mode door (which is rotated by the mode and blend door actuators)