Furnace Not Blowing Hot Air – Explained | Repair and Replace

Furnace Not Blowing Hot Air – Explained | Repair and Replace


Hi, I’m Vance and welcome to Repair and Replace. If there’s cold air coming out of your heat
registers, then here are a few things you should check. If the furnace blows cold air, first check to see if your thermostat is set
to heat, and if the fan is set to Auto. If the fan is set to “ON” it will blow air
100 percent of the time. It’ll circulate heat when needed, and then will continue to circulate room temperature
air throughout the home. If the furnace ignites, the blower fan runs,
but the furnace shuts off before the house warms up, then it could be
a problem with the limit switch. The limit switch monitors the temperature
of the air passing over the heat exchanger and will shut off the furnace
if the system overheats. The gas will be turned off and the blower
fan will continue to run for several minutes to help the heat exchanger to cool down. If the limit switch fails, then the furnace
will shut off before it gets a chance to warm up, causing cold air to come out of the vents. The limit switch can be tested for continuity
to see if a continuous electrical path is present. If the switch has continuity, the multimeter
will show zero ohms. Even if the limit switch shows continuity,
it might still be faulty. As a limit switch fails, it can start shutting
the furnace off at lower and lower temperatures. so if the limit switch has failed or is starting
to fail, then its best to replace it. And you can see how to do this
in the video linked below. If you liked this and want to see more tutorials and informational videos,
then subscribe to our channel. And if you need help, you can call or visit
an AMRE location to talk with our knowledgeable staff. Thanks for watching.

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