Furnace Will Not Turn on With Thermostat [6 Easy Fixes]

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The last thing you want to do is go home on a chilly day and discover that your furnace will not turn on with thermostat. Frustrating as it may sound, you should probably be able to sort out this issue by the end of this article.

Furnace blowing warm air
Furnace thermostat

There are several reasons your furnace won’t turn on but a lot of these are things that you can easily tap your hands on and get them sorted out. But for others, you will need to call professional guys to come and give hand, of course at fee. Let’s now get a little bit into details on why your furnace won’t kick on with your thermostat.

6 Reasons Your Furnace Will Not Turn on With Thermostat

So, the weather is killing cold, and you look up to your thermostat for some heat only to discover that your furnace is not turning on. Here is a list of things that you need to check first when you have that problem:

1. Thermostat Battery

When you try to turn on your furnace on your thermostat and it won’t turn on, you might want to check the batteries. 

If your thermostat relies on battery power to work, at one point or another, the battery will become low and eventually die. You’ll be surprised to learn that a battery does not to completely die for it to cause the thermostat to malfunction. Signs of a low thermostat battery include.

  • Difficulties turning off and on of your furnace
  • Your furnace not responding to heating and cooling instructions from your thermostat
  • A blank screen on your thermostat.

Solution: A solution to a low battery is simply a replacement of the battery with a new one. Generally, batteries in a thermostat can stay for about a year without changing.

2. Thermostat Compatibility Issues     

If you have checked with your thermostat battery and other thermostat issues and everything looks great, it’s time you took a closer look at your thermostat’s compatibility with your furnace.

 Most newer and programmable thermostats have compatibility issues with older heating systems. Another issue could be if you carried out the installation of the thermostat yourself.

It possible that you mixed things up somewhere while installing it. But no matter how bad of a mess it could be, a call to a professional technician will get everything sorted out in no time.

3. Furnace Won’t Turn On Because of a Switch or Circuit Breaker

If your thermostat is compatible with your furnace but still your furnace is not turning on, then you will need to check your furnace power switch or the circuit breaker. Find out if the furnace power switch is on. If its off, reset it. If it’s on and the problem is still there, then go the circuit breaker.

A circuit breaker might have tripped as part of your heating system’s safety measure. If it has tripped, reset it. Usually resetting your circuit breaker should bring back your furnace. If it keeps tripping, never tape it (don’t do that) instead, call a licensed HVAC professional to come and say what to do with what.

4. Clogged Air Filters

Clogged air filters are the commonest culprits to any major furnace problems. Clogged air filters can damage the heat exchanger and other important components of your furnace.

 If your furnace won’t turn on, it could be a sign of damage to the pilot light, fan, pressure switch, gas valve and other critical parts of the furnace. Damage to all these components is largely caused by a clogged air filter. Below are some of the things you need to take note of, about furnace air filters:

  • You need to change air filters once every 3 months (more even better)
  • Changing air filters will keep your heating system running efficiently and prevents unexpected costly break downs.
  • You need to check the size of your furnace air filter before getting a new one and you need to put it in the correct position, and in the right direction of air flow.

5. Pilot Light Is Not Working

The pilot light is responsible for igniting the burners. If it’s not working or there is no gas supply, then it won’t come on. Because of that, there will be no combustion in your furnace and your furnace won’t kick on.

6. Dead Blower Capacitor Could Be The Reason Your Furnace Won’t Kick On

A blower motor forces the air into the heat exchanger and into the ductwork of your home. If the blower motor is not working, then you will not have the heating or cooling in your home.

Usually when there is some type of noise coming from the blower compartment such as buzzing or humming noise, it’s a sign that the blower capacitor is bad or dead. A dead blower capacitor could be the reason your furnace is not turning on. In this case, you need to replace it with a working one

Because this could a involve a bit of technical knowledge, calling HVAC professionals to come and examine those parts is in order.


Why is the heat in my home not working?

There are so many things that can stop heat from working in your house. The first thing you need to find out is if your heater is turning on. You can do this by:

  • Checking if the power switch for your heater is in the on position. If it’s not, put it in the on position and check if your heat will come on.
  • If the power switch is on but your heater won’t turn on, check the circuit breaker for your furnace. If you are using a heat pump, check if the circuit breaker for the outdoor unit has not tripped. If it has tripped, reset it. Sometimes, when the heat pump is defrosting, it will not give you the heat for few minutes, but you should start getting the heat in about 10 minutes or so.

After checking with the power switch button and the circuit breaker but everything looks fine, and your thermostat is on but still no heat, move on to the next tip.

Why is my thermostat on but no heat?

There are several reasons you could have no heat when your thermostat is on. This is what you need to check first:

  1. Thermostat settings: The first thing you want to do is check if your thermostat setting is not on ‘cool’ mode. If it’s on the ‘cool’ mode, it will prevent your heater or furnace from heating. You need to change settings to ‘heat’ or ‘auto’.
  2. Air filter: If your thermostat is set correctly but you still don’t have heat coming on, you need to check your air filters. Clogged air filters could be the reason your furnace will not turn on with thermostat.  Dirty air filters will restrict airflow into your heater, and this will cause overheating and eventually shutting off the heating system. Check if you have dirty air filters and change them if necessary.


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