When your air is running you are getting water on the floor under the furnace what should you do?

Investigate the way in which condensation is being moved away from the heat exchange. Air conditioning dehumidifies the air as it cools it. The moisture from the process needs to go someplace. Usually there is a pipe that takes it to a sump pump or drain. This could be clogged. Or if it wasn't installed with a drain, you may need to install a condensation pump.