There are several reason why a central heater might blow cold instead of warm air and these include a blown out pilot light, an overheated furnace or its thermostat is set to "On." These three issues are the most common causes of why a central heater will blow cold air and the ways to fix these issues are relatively simple.Continue Reading
The following are the three common reasons why a central heater blows cold air and how to troubleshoot and fix the issue.
Blown out pilot light
A pilot light is a small flame that is constantly lit within a furnace and is on standby to light up the furnace when the homeowner turns on the heater. Follow the instructions that came with the heater's manual in relighting the pilot light. If the pilot light refuses to light up, check if the gas valve is set on "On" or if the pilot light needs cleaning.
An overheated furnace also causes cold instead of warm air to come out of the vents. This is because once the furnace gets too hot, the high temperature triggers the limit switch that turns off the burners but keep the blowers running to cool the furnace before shutting down. Dirty furnace or air filters are the common causes of overheating furnace and cleaning them out will usually solve the problem.
Thermostat set on "On"
If the setting of the thermostat is set on "On," the blower will keep on releasing cold air. Adjusting the setting to "Auto" will solve this simple issue.Learn more about Heating & Cooling
An electric heater might blow cold air because the thermostat is set too low or is not working properly, the air has not had enough time to warm up yet or there is leaky or blocked duct work. Most of these are easily determined and corrected by the homeowner.Full Answer >
An electric furnace may constantly blow cold air when it has a broken switch, thermostat problems or one or more broken heating elements. The high limit switch may be stuck open as well.Full Answer >
A gas furnace that does not start sometimes requires relighting the pilot light. After waiting a few minutes for fumes to clear the area, the owner can turn the dial to pilot, press the red button, and light the pilot. Holding the button down for 30 seconds warms the thermocouple.Full Answer >
To troubleshoot gas furnace burners that do not ignite, inspect the pilot light, ensure the gas valve is on and perform other common troubleshooting tasks. Review the owner's manual for model-specific troubleshooting instructions.Full Answer >