I had my heat set to 70°F all day and my gas furnace was blowing out warm air. Then out of nowhere, it started blowing out cold air for the past 3 hours. I tried turning off the furnace and turning it back on but it still blows out cold air.
Why is the gas furnace now continually just blowing out cold air
furnacegas
Related Topic
- Would a failing igniter cause the furnace to blow cold air
- Why is the new high efficiency furnace blowing cold air sometimes
- Gas furnace air is cooler (but NOT COLD) during bitter cold days – why
- Furnace blowing cold air
- Gas Furnace blowing hot air into room, flue is cold
- After blowing heat the fan won’t stop, continue blowing cold air for prolonged period of time (30+ min)
Best Answer
If the furnace is constantly blowing cold air, it's likely one of two problems. The first is easy to check and fix, the second will likely require a service technician. Start by checking the thermostat, to make sure the
Fan
setting is not in theON
position. If the fan is set in theON
position, the fan will blow air continuously. Make sure the fan is set toAUTO
, which will allow the furnace to control the blower.The other reason a furnace blower will run continuously, it that the high limit switch is dead or dying. If the high limit switch fails, it will "fail open". This causes the furnace control board to think the furnace has overheated, so in response the control board turns the fan on to clear the heat. The most common cause of high limit failure is constant overheating, which is usually brought about by dirty filters. You'll likely have to contact an HVAC Technician to replace the high limit switch, since it might be difficult for you to locate the part yourself. In the future, make sure to check your filter and change them as often as needed.