Heat coming out of vent in floor?

I have the exact same coach! Previous poster is correct, your coach heater is on. It's an option on Winnebago/Itasca motorhomes called motoraide, the engine cooling system has a secondary heater core to help heat the rest of the coach behind the cab. You'll also find a vent in the bedroom & maybe the kitchen also! It also routes coolant around your water heater, if you drive the RV around a few minutes & turn on the water pump and open a faucet, you'll have hot water even if you didn't have the propane or electric heater on! Handy little option to have, especially traveling in cold weather to save propane running the furnace while driving! Motoraide has been around since the '70s, but for some reason isn't standard on all motorhomes,never could figure out why...