Mike, if all TVs are snowy, I would first suspect something with the antenna booster. There are many paths to take but I would start by making sure the booster is off if you are trying to use cable. IF the booster is off and you still have problems, you will have to start checking connectors. Pull the antenna amplifier out and check there first. Another area to check is behind the UDC where the coax cables attach to the back side of the connectors in the UDC.
I used an ohm meter to check all the connectors in my rig. There were several bad ones. Sadly, this is one area that is usually missed at the dealers pdi and Heartland really needs to do a better job on their end as well.