Why is my Furnace Not Turning On?

While summer is quickly approaching there are still some cool nights remaining here in Toronto. Your furnace has been running great all through winter and you are taking it for granted when all of a sudden you notice your house feels cold. It’s cold enough that the heat should be running, but your furnace just isn’t kicking on. The last thing that anyone wants to deal with during a cold spell is a furnace that will not turn on.

If you find yourself in this situation try these easy troubleshooting options. You may also want to consider calling an HVAC company to make sure they aren’t signs of larger problems and that you won’t have issues come Fall:

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  1. Check your thermostat. This might seem self-explanatory, but this is frequently the solution. Make sure that your system is set to heat. During the transitional weather of spring and early summer it is not uncommon to want to run your air during the day and your heat at night. If you do not have a system that you can set to automatically transition between the two, you will want to double check that you have your heat turned on. While you are at your thermostat do a quick double check to verify that it is really cold enough in the room for your thermostat to call for heat.
  1. Check your circuit breaker. Your furnace, even if it runs on gas or propane, needs electricity to run. If your system isn’t kicking on you can head to your electrical box to check that you don’t have a popped circuit. If everything looks good in the box move on to step 3.
  1. Check for the pilot light. If your furnace has a pilot light, now is the time to check that it is still it. There are many reasons that a pilot light might go out, so check to make sure that yours is still it. If you find that the pilot light is out take the necessary steps to relight it. If you get it lit recheck your system to see if the heat kicks on. If not, keep trouble shooting.
  1. Look at your air filter. Changing the air filter on your HVAC system is something that should be a part of the regular maintenance that you do in your home to keep your system running properly. Neglecting to change the filter can lead to a dirty and clogged filter that restricts the flow of air passing through. If your furnace is not getting enough air through the filter it could be the reason your heat isn’t kicking on. If you filter looks dirty and clogged try putting in a new filter to see if that remedies the situation.
  1. Check your fuel supply. If you have worked through the above steps, it is time to check your fuel supply. If you have propane take a moment to verify the percentage of propane in your tank. Not tracking the levels could have resulted in running out of propane and the inability of your furnace to provide heat. Check to see if your other appliances that use the same fuel source are still running. If they aren’t, then you will want to contact your gas or propane company.
  1. Look at your furnace unit. Green lights on your furnace indicate a system that is working properly. If you usually have green lights and now you don’t see any lights, or you see a red light, it is an indicator that there is a problem with the unit. If you find yourself in this circumstance, call in a professional to check your HVAC unit.


While these are some of the easier to spot situations that could be causing your furnace not to turn on, there are many other problems that could be the cause. There are stories of everything from chewed electrical wires in an attic or beehives being built in the PVC pipe running from the system. If you run through these trouble shooting steps and aren’t able to locate the problem it is best to call and speak to a  qualified professional from Lloyd HVAC.

There are many reasons that your heat might not be kicking, let Lloyd HVAC help keep you warm and your heat running.  Lloyd HVAC is a Toronto based HVAC company and offer free, in-home estimates for the entire GTA.