What Are the Common Causes of a Furnace Not Turning On?

Picture this: it’s a chilly winter morning, and you’re eagerly anticipating the warm embrace of your cozy home. However, your furnace decides to play truant and leaves you shivering in the cold. A furnace not turning on can be frustrating and uncomfortable, especially during the colder months. 

In this blog post, we’ll explore the common culprits behind this issue and guide you on how to address them. Remember, when in doubt, it’s always wise to seek professional assistance.

Thermostat Troubles for furnace not turning on

Check Thermostat Settings

Your thermostat might be the simplest yet often overlooked culprit. Ensure that it’s set to the desired temperature for heating. Sometimes, accidental adjustments or someone in the household changing the settings can cause the furnace not to turn on.

Replace Batteries

If your thermostat relies on batteries, replace them regularly to guarantee proper functioning. Weak or dead batteries can cause communication issues between the thermostat and the furnace.

Electrical Issues for furnace not turning on

Check Circuit Breakers

Furnaces often trip circuit breakers due to power surges or electrical issues. Locate the circuit breaker for your furnace and ensure it’s in the “ON” position. If it has tripped, reset it and try turning on the furnace again.

Inspect Wiring

Inspect the furnace’s electrical wiring for any signs of fraying, damage, or loose connections. If you’re uncertain about handling electrical components, it’s safer to call a professional electrician for assistance.

Pilot Light or Ignition Problems for furnace not turning on

Relight the Pilot Light

For older furnaces with a pilot light, follow the manufacturer’s instructions to relight it. If you’re unsure or uncomfortable doing this, it’s best to contact a professional to handle it safely.

Check Ignition Systems

For newer furnaces, if the electronic ignition system is failing, it will need a technician to diagnose and repair the issue. Attempting to fix this on your own could potentially cause more damage.

Gas Supply Issues for furnace not turning on

Verify Gas Supply

Make sure the gas valve supplying the furnace is open and functioning correctly. If you suspect a gas supply issue, do not try to address it yourself. Call a professional immediately as working with gas can be dangerous.

Air Flow Obstructions for furnace not turning on

Change/Clean Air Filters

Regularly changing or cleaning your furnace’s air filters is essential for proper airflow. Dirty filters can block airflow and cause the furnace to shut down to prevent overheating.

Inspect Vents and Ducts

Ensure that all vents and ducts are open and not blocked by furniture or other objects. Proper airflow is vital for the furnace to function efficiently.

Pressure Switch Issues for furnace not turning on

Professional Diagnosis

Pressure switch problems can be complex and require a professional HVAC technician for accurate diagnosis and repair. They have the expertise and equipment to troubleshoot these components effectively.

Malfunctioning Blower Motor

Professional Replacement

If the blower motor is malfunctioning, it’s best to have a certified technician assess its condition and replace it if necessary. The blower motor is a critical component for proper air circulation and heating.


When dealing with a furnace that refuses to turn on, it’s essential to approach the troubleshooting process carefully and, if needed, seek professional assistance. Regular maintenance, awareness of potential issues, and timely intervention can ensure your furnace operates efficiently, keeping you warm and comfortable during the cold months. 

Remember, when in doubt, reach out to an HVAC professional to diagnose and fix furnace problems accurately. Stay warm and cozy!