Reasons why your thermostat might be blank: the first one is you might have a float switch that has killed power to that therat and what I mean by that is when we install heating and air systems. There are literal switches that are on that system that will open or turn off if there is a problem. So some of these float switches might be mounted, say, on a drain pan. Some of them might be actually mounted in the line of the drain itself.

Some of them might be connect ected to say, a condensate pump. Different types of float switches out there, but no matter which type you have, if there's an issue, it is meant to shut the system down.