I have a 2003 F-150 XLT STX, 5.4L and its had a slight buzzing under the dash for many years that I have heard occassionally. Recently it is louder and non-stop. It happens as soon as the ignition is turned on and happens with the engine off or on. It does not matter if the heater/AC is on or off. I removed the plastic cover under the center of the dash, right near the carpet. There is what looks like a white electrial box connected to the bottom of the black heater plastic housing area. Unplugging this white connection going to it makes the clicking stop.

What is this white connector / white box and what could be causing the buzz / clicking noise that is coming from it or around it when the ignition is on? Photos below