Winter is on its way. You’ve changed your filter, gotten your annual tune-upand done everything you need to prepare for the heating season. So then why is your furnace blowing cold air? There could be any number of reasons.

First, wait a minute or so to see if the air heats up. When you turn your furnace on, it takes a few seconds for the warm air to reach your vents, and it may blow cold air in the meantime. This is nothing to worry about.

If that’s not the problem, see if the unit’s fan is set to “on.” If it is, that means your system is blowing air into your home whether the furnace is on or not. Switch it to “auto,” to make sure it only blows when you need heat.

If you have an older gas furnace, the pilot light could be out, so the air isn’t getting heated before it circulates. There should be a panel or a small door on your furnace where you can access the pilot. Turn off the gas, wait a few minutes for fumes to disperse, and then follow the furnace instructions for relighting the pilot.

Maybe the furnace is blowing warm air when it first goes on, but then it quickly goes cold. In that case, the problem is likely the flame sensor. The flame sensor makes sure the fire is burning when the furnace is on. If it isn’t, and fuel is still being fed into the furnace, it could cause an explosion. If the sensor doesn’t detect a flame, it stops the burner as a safety precaution.

Dirt on a sensor can hinder it from sensing the flame and keep your burner from staying lit. If this is the case, call in a professional to clean your flame sensor.

Or maybe none of those is the problem. It may be something more complicated, in which case you should call a professionalto get your furnace back up and running.

For help fixing your furnace when it’s blowing cold air, contact Bill Joplin’s Air Conditioning & Heating. We serve clients throughout McKinney, Frisco and Allen.