Wondering why your heater is blowing cold air? It might sound silly, but the thermostat is the first thing you want to look at. Confirm the system is set to “auto and not “on.” If the thermostat is set to “on” then your heating system will blow continuously, even when it isn’t heating the air being released, thus blasting cold air. Flipping it to “auto” will make sure the heating equipment only blows when it’s really heating the air to keep your home warm and comfortable.