specwarGP2
Regular
I'd guess it's either mechanical or electrical. The heating/contracting sounds bogus to me if it happens within a few seconds of turning it on. More on the side of mechanical than electrical, because usually if you get snapping sounds bad things happen in the electrical world. The sound people are describing does make me think of a quick electrical discharge.
Does it continue to snap as the unit is on?
Yes it makes a fairly noticeable snapping/cracking sound randomly when it's on. It's very strange. So is the consensus that it's nothing to be worried about, right?