Hmmm, can't ever remember any clicking except for something trying to light, like the fridge or hot water heater. But if it stops when you unplug then that wouldn't make sense.
One note, even if it has been plugged in and everything is off, there are still "phantom" draws unless you have installed your own battery disconnect. Keystone factory disconnects don't "disconnect" everything. But not sure why the converter would be clicking.
2014 Raptor RP300MP w/ Rear Patio Party Deck, Folding Side Ladder, 6 Point Level Up, Carlisle Radial Trail HDs
2004 2500HD D/A CC SB - TTT Mirrors, Prodigy BC, 18K Pullrite Superglide, NEW Fuel Injectors 11/2015 (ouch)