I was told when I bought the Fx5 that the start time for the 24 hour purge starts when you first plug it in. So if you plug it in at 5pm then the next day at 5pm it should do its purge. What happens w/ mine if I plug it in at 5pm then the next day it does its purge around 5:36 then the next day it would be around 6:15pm...etc... Does anyone know if I have a defective motor unit or is this normal operation? Thanks!