Furnace Will Not Turn On With Thermostat

image of a homeowner feeling chilly due to furnace not turning on with thermostat

People rush to their thermostats the moment they can’t tolerate the frigid temperatures. All they need to do is press some buttons that should switch the furnace on and begin the heating cycle. After several minutes, warm air should flow throughout your home and provide relief and comfort. It is a reliable system utilized by millions of households. However, a few might encounter problems like a furnace will not turn on with thermostat. This can cause anxiety and dread, especially if it happens in the middle of winter. This article discusses the reason behind this issue and what you can do about it.

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My Furnace Won’t Turn On With The Thermostat

Regular furnace maintenance can prevent this issue from happening. The yearly checkups from professional HVAC technicians are usually scheduled in the fall, so you can be sure that your furnace is winter-ready. The HVAC tech will inspect your system for any imminent failure, signs of wear, excessive dirt, safety hazards, and other likely problems. Your furnace will work as it should when these problems are taken care of immediately. If you haven’t had your heating system professionally maintained yet and it won’t turn on, it might be due to any of the following:

Thermostat Issue

The thermostat is the system’s command center. Therefore, it is only logical that all troubleshooting steps should begin here. The thermostat might be failing if the commands you input aren’t getting through. This could happen in several ways.

Thermostat Settings

image of homeowner adjusting programmable thermostat depicting furnace not working with thermostat

Machines are designed to heed commands. Check the thermostat settings if they are working differently from what is intended. It might be what’s causing the problem. For instance, the thermostat setting might be at COOL or OFF. Set the thermostat to HEAT when you need warm air from your furnace. Take a look at the exact temperature settings as well. It might be too low to have a discernible effect. Consider setting the temperature five to ten degrees higher and see if you feel any difference.

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Thermostat Not Receiving Power

If the thermostat settings are okay, you have to look for other causes. The problem might have something to do with power. The thermostat might have a dead battery, so you need to replace it with fresh ones and try again. The furnace might switch on right away after this. Otherwise, you might have a faulty power circuit. Let the technicians handle it. They can diagnose the issue and give you their professional recommendations.

Wrong Thermostat For Furnace

Thermostats come in many various types. A thermostat will only work if it is compatible with your system. If the thermostat installed doesn’t match the furnace’s capacity and capabilities, it might result in sub-optimal performance. Miscommunications between the furnace and thermostat can happen, leading to frequent failures. Do extensive research or consult an HVAC professional before buying a thermostat.

Bad Furnace Wiring

close-up of thermostat wiring

Power and command signals pass through a network of wires. These wires can get frayed, come loose, or suffer damage as time passes. Bad furnace wiring can sever the connection between the heating system and the thermostat. It is a common problem that deserves attention. If you are knowledgeable about wiring, check it at least once a year. You can also hire HVAC professionals to do this as part of the yearly maintenance.

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Clogged HVAC Air Filter

HVAC air filters trap dirt, dust, and other debris for better indoor air quality and extended system lifespan. However, they can only absorb so much dirt until the airflow is severely compromised. When this happens, replace the clogged air filter. The system’s performance and efficiency will significantly drop if you don’t do this. It could also cause the furnace to shut down due to the strain. It is recommended that you check the HVAC filters at least once a month and replace them as needed. Buy compatible filters in bulk to make this task easier.


Tripped Circuit Breaker

Furnaces might use heating oil, gas, or propane to operate, but parts of the system utilize electricity. The circuit breaker protects your furnace from power surges and other anomalies. The circuit breaker might be the issue if your heater suddenly stops working. Check all breakers connected to your system to see if they are in good working condition. Look for the furnace switch to determine if it’s in the correct position as well. Accidental movements might have switched it off. If this is the case, put it back to the right setting and try again.

Furnace Belt Or Blower Problem

In some cases, your furnace might be working, but some issues might be pointing to a major problem. For instance, you might hear a noise from your usually high-pitched blower. This component might need a fresh lubricant application. It could also be that the belt is worn out and needs replacing. Leave this matter to the professionals to ensure an effective and lasting solution.


Check the Furnace Drain Pan

HVAC systems remove moisture from the air, reducing indoor humidity in the process. The water is collected in the drain pan and automatically flows out. However, this channel might develop a clog and prevent proper flow. The water pump might also fail to move the moisture. This will keep the pan full of water, which can trigger the float switch, preventing the furnace from switching on. Therefore, you need to empty the drain pan and ensure that the water pump works as intended.

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Furnace Pilot Light

gas furnace flame

Most heating systems will not switch on if the pilot light is out. This can happen because of system issues, tripped failsafe, and drafts. Furnace ignition won’t occur without a pilot light. Check the manufacturer’s manual to learn how to relight your furnace’s pilot light. Typically you can relight it with a few simple steps. First, remove the access panel and find the pilot light assembly. Turn the reset switch off. Wait for 10 minutes before turning the switch to PILOT so that fuel can flow. Use a match to relight it. Call a qualified HVAC technician to help you should the problem persist.

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Furnace Fuel

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All furnace components might be working correctly. However, it still won’t produce heat if there is no adequate fuel supply. Therefore, check the oil or gas supply of your furnace.

  • Heating Oil Tank or Propane Tank is Out of Fuel: Propane and heating oil are stored in your property via tanks. Contact the delivery company for a refill before the fuel level runs too low. Track your usage habits to find out the amount you need and when to order more.
  • Issues with Natural Gas Supply: If another appliance in your home relies on the same fuel, check if it still works. This will help you determine if it is a supply issue. Examples of fuel-powered appliances are the water heater or stove. Contact your fuel supplier to help you if there is an interruption in your fuel supply.
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Heating systems should be controlled without problems when using a thermostat. If your furnace doesn’t work regardless of what you do, go through the list mentioned above to find out what’s wrong. You can also ask for help from professional HVAC technicians to save time and effort. With their expertise, you can understand the problem more thoroughly, and the system will be back to normal immediately.

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McAllister Energy

McAllister Energy offers high-quality HVAC services in Camden County, New Jersey. We hire only the best, professionally certified technicians who conduct superior heating and cooling services. Some of our HVAC services include HVAC maintenance, heating and cooling installations, repairs, ductless systems, energy audits, and much more. All our techs provide accurate HVAC services on time, every time.

Our company guarantees affordable heating and cooling service rates. Our maintenance services can increase your home’s comfort, energy efficiency, and cost-effectiveness. We can also provide you with a highly energy-efficient HVAC replacement system that fits your budget. Your satisfaction is important to us, so all our work comes with a guarantee. Book a service appointment with McAllister Energy today. We provide free, in-home estimates.

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