What to do when furnace is not heating:
I’m going to give you three simple things to check if you’re experiencing a problem with your furnace. If your furnace does not heat there are some simple checks you can do yourself that may fix the problem.
First let’s check the thermostat.
Don’t touch it. Don’t make any adjustments. Just look to see, is it properly set on heat? There is a heat/cool/off system switch that should be in the heat mode.
Is the temperature setting set above the recorded room temperature? The term for that is is it calling for heat. Is the thermostat telling the furnace, yes I need you on? Sometimes your programmable thermostat will make a change and you weren’t aware of a change.
Next, do you have power to the furnace?
If your furnace is not working, you want to make sure you have power to the furnace. There’s a real simple way for you to check to see if you have power to the furnace. On your thermostat there is another switch for your fan. It will either be marked “fan” or “blower” and it has two settings: Automatic and on. Some have a “circulate” mode but typically just two.
Set your thermostat to the “on” position.
Set your thermostat to the on position. You are telling the blower to come on and run non-stop.
When you switch your thermostat to “on” you should hear the furnace blower come on. If you go to a nearby register you should feel air blowing out of the register. If you do not hear the furnace come on or feel air blowing, we know that there is a power issue. We gave it a direct call for the blower to come on, and if nothing happens, there is a power issue.
Do a hard reset of the furnace if your furnace is not heating.
The third thing you can do yourself if your furnace is not heating is to do a hard reset of your furnace. Many furnaces today have multiple circuit boards on them. These appliances have many safety controls that can sense whether your furnace is having a problem or not. If it is sensing a problem, the furnace can lock itself out. What we can do is we can reset that by simply removing power from the furnace.
There should be a power switch, an external power switch on the side of the furnace. It looks much like a light switch that would be on the wall. If you don’t see a switch, your furnace may be powered with a service plug. Power it off and count to ten seconds. Plug it back in and see if it comes back on. (If your furnace is powered by a plug, you can test the power by plugging in something else such as a lamp to check the power.)
After you have done a hard reset of the furnace it should have cleared out any faults that could have been triggered that kept the furnace off. Now that we have “cleared” the furnace so to speak, we should have a good call for heat.
You should hear action in the furnace now.
If after all these checks and your furnace is still not heating, it’s best to call a professional. You checked the simple issues. You can tell your service technician what you have done for troubleshooting thus far that will help them with diagnosing the problem from there.