We put a humidifier on our furnace before the winter in 2012 here in Michigan. During the winter, I noticed that ice cycles were forming on the vinyl siding (east facing) second floor and running down the siding. In the fall of 2012 we also remodeled our second floor bathroom and put a new exhaust fan in that exhausts out the same side as the ice cycles. I thought maybe that was causing the ice cycles. I've noticed recently that the ice cycles are now above the exhaust port. Anybody have any idea what is causing the ice cycles? Could this have something to do with the humidifier? Didn't have these forming prior to the installation of the humidifier. Hmmmm...