The wires are connected correctly and the fan will not stop running. I put the old thermostat back on the wall and the fan would not stop running and I bought a third thermostat and the fan will not stop running. Cool air is also coming for the vents. What is wrong?

Its hard to say,not knowing what kind of equipment you own,I can`t seem to find the name brand or the model numbers of the furnace or the thermostat. Maybe you could type it in again maybe in bigger letters for me and others to see better
Are you for sure the tstat is set on auto and not fan,this can and has happened to many and can be overlooked,, let us know something

If your furnace is a gas furnace it is possible that you have a problem with a transformer, if the transformer is bad the furnace fan will run all of the time.

Try this, unplug your furnace for about ten seconds, if it is gas, and then plug it back in. Watch and listen to what the furnace does and then post back with the information.

Man, we seem to get this scenario a lot... :rolleyes: