Cg, (1) what's "end of the run, (2) how any wires come to it and (3) do the light and fan come on and off together
Forgive for my ignorance of techs' terminology
My guess is that there's something wrong. (1) what are you measuring with respect to (neutral? gnd?) and (2) is the voltage abnormal (that is slightly higher or lower than line)
Shouldn't it always register hot?
That's the way a power switch is usually wired, yes. However, if there's no malfunction it's likely there's a semiconductor unit somewhere that senses the switch position and control the lights accordingly