Why is Your Furnace Blowing Cold Air?
All gas, oil, and electric furnaces are sensitive and calibrated equipment. It only takes one or more components to be out of whack or not tended to, creating problems. One of the more vexing and mysterious problems the Chicago HVAC specialists at Aircor see is when your furnace blows cold air when the heat is on. Or it could be the opposite: you feel cold air coming from vents when the heat is off. Whether you own a gas, electric, or oil furnace, troubleshooting why your furnace is blowing cold air instead of heat is where you should begin before calling in an HVAC contractor. Below, we give you some basic troubleshooting steps to help you figure out why your heater is blowing cold air in the house. Thermostat SettingAt the top of the troubleshooting list is first to check your thermostat. If you notice the thermostat is set to ON, it is most certainly the problem. What’s occurring is your heater blower continues to operate, although your home has reached its maximum comfort level. The solution? Reset the thermostat to AUTO.
Now, the furnace will automatically shut off the blower once your home has been thoroughly warmed and come back on when it needs to raise the temperature again. Overheated Furnace If your furnace is blowing cold air sometimes, it could be that your central heater is overheating. What causes this to occur is the limit switch shuts off the furnace blowers. It does this to stop the overheating, reducing the temperature to a non-dangerous level. What’s behind an overheated central heater? Most likely, it is a grimy filter. An obstructed filter will limit airflow, motivating your gas, electric, or oil furnace to take more time to heat the living spaces, causing overheating. You can replace the filter and find out if it resolves the issue. If you own an oil furnace, changing the filter is more complex and dirty, so contacting an HVAC pro to do it for you is the better option. Since we’ve mentioned oil furnaces, another reason your oil furnace blows cold air is that the oil tank may be empty. The oil furnace will blow cold air instead of heat without fuel to light the burners. Pilot Light Issue: If your central heating is not blowing hot air in the house, an unlit pilot light may be the cause. There are three approaches to dealing with an unlit pilot light:
Try relighting the pilot light. If the flame catches and remains burning, then the problem is solved!
Pilot light won’t fire up? Check the gas valve switch to see if it is on. If it’s on, inspect the pilot light to see if debris has accumulated and clean it. Cleaning the pilot will permit gas to flow to it.
If the pilot light ignites but goes out again, the thermocouple is at the heart of the matter. Adjustment or replacement is needed. If you’re mechanically inclined, go for it. Otherwise, contact a heating contractor.
Condensate Drain LinesIf you’ve purchased a high-efficiency furnace the condensate drain lines may be plugged up, keeping the burners from initiating. Burner ProblemsIf your oil or gas furnace burners have built-up dirt it could also prohibit the burners from igniting and the furnace blowing cold air. Ductwork Problems: The ducts of your central heater could be causing the problem of the blower not blowing hot air in the house. Causation might be holes and leaks in the ductwork, allowing warm air to escape and the furnace to blow cold air instead of heat.