Furnace Won’t Ignite? Discover 5 Possible Causes and Solutions

Furnace Won't Ignite? Discover 5 Possible Causes and SolutionsIf your furnace won’t ignite, there could be a few reasons why. This is a common problem with furnaces, but one that is luckily fixable most of the time. In Illinois, you need your heating system to get through the winter. It’s one of the most important parts of your home.

In my years 20+ years of working in the HVAC field, I have repaired, serviced, and replaced all different kinds of furnaces. I’ve worked with gas furnaces, electric furnaces, and some old oil furnaces as well.

In this article I’ll go over some of the most common reasons and fixes when a furnace won’t ignite. If you are having trouble with your furnace in Hoffman Estates, IL or the surrounding areas, give us a call at (630) 504-8688, or contact us online. We can help you get the heat back on in no time!

Dirty or Clogged Filter

What To Do

A dirty or clogged filter is one of the most common reasons a furnace won’t ignite. The air filter in your furnace is responsible for removing dirt and airborne irritants from the air. Over time, these filters can become clogged with dust and debris, restricting airflow and causing the furnace to work harder than necessary. This can lead to overheating and prevent the furnace from igniting. It also makes the air in your home dirtier and less healthy.

If Your Air Filter Is Clogged, It Could Be Causing ProblemsSolution: Luckily, this is an easy fix you can take care of yourself. Regularly check and replace your furnace filters. A general rule of thumb is to replace them every 1-3 months, depending on usage and the type of filter. If you have pets or live in a dusty area, you may want to change them more often.

Thermostat is Broken or Has No Power

What To Do

If your furnace is not igniting, it could be due to a malfunctioning thermostat or a lack of power supply to the thermostat. Thermostats regulate the temperature in your home by signaling the furnace to turn on and off, and letting it know if the home has reached the desired temperature.

Solution: First, check if the thermostat is turned on and set to the correct settings. Ensure it’s set to ‘heat’ and the temperature is set higher than the room temperature. If this doesn’t work, check the batteries in a battery-operated thermostat or the circuit breaker if it’s hardwired. If you get stuck, call in a professional.

Gas Burners are Dirty

What To Do

Dirty gas burners can prevent a furnace from igniting. Burners that are clogged with dirt and debris can obstruct the flow of gas, making it difficult for the furnace to light.

Solution: Turn off the furnace and carefully clean the burners. It’s often best to call a professional to handle this, as it involves working with critical components of the furnace. This is something that is performed when you schedule routine furnace service.

Pilot Light or Ignitor is Broken

What To Do

Older furnaces use a pilot light, while newer models use an electronic ignitor. If either of these components is faulty, your furnace will not ignite.

Solution: For a pilot light, check if it’s lit. If not, try relighting it following the manufacturer’s instructions. If it doesn’t stay lit, you may need to replace the thermocouple. For an electronic ignitor, it’s usually best to call a professional for replacement.

Furnace Blower Comes On But Won’t Ignite

What To Do

Sometimes, the furnace blower comes on, but the furnace won’t ignite. This could be due to a variety of issues, including a faulty blower motor, a problem with the control board, or issues with the flame sensor.

Solution: We would say let the pros handle this one. It requires professional diagnosis and repair, as it involves some more complex components of the furnace system.

Flame Sensor is Malfunctioning

What To Do

The flame sensor is a safety device that detects whether the burner is lit. If it’s malfunctioning or dirty, it may fail to detect the flame, causing the furnace to shut down as a safety precaution.

Solution: Cleaning the flame sensor might solve the issue. If this doesn’t work, the sensor might need to be replaced.


What To Do

Drafts in your home can blow out the pilot light or affect the efficiency of your furnace, leading to ignition problems.

Solution: Check around your home for drafts, especially near windows and doors. If your furnace is in the basement, like most are, make sure your windows down there are sealed tight. Use weather stripping or caulk to seal any gaps. This is also going to help you save energy and stay more comfortable in your home.

Issues With Your Gas Line

What To Do

Problems with your gas line, such as leaks or blockages, can prevent gas from reaching your furnace, making it impossible for your furnace to ignite. This is probably tougher for you to diagnose, and luckily not a very common issue.

Solution: If you suspect a gas line issue, it is critical to call a professional immediately, as this can be a safety hazard.

Relighting A Furnace Pilot Light: How-To Guide

If your furnace uses a pilot light and it has gone out, you can usually relight it yourself. First, locate the pilot light assembly and turn the knob to ‘pilot.’ Hold a lit match to the pilot opening while you push the reset button on the pilot control panel. Once the pilot light stays lit, turn the knob to ‘on.’

If you are in need of a furnace repair in Hoffman Estates, IL, or any of the surrounding areas, we can help. Just give us a call at (630) 504-8688, or contact us online and someone will get back to you right away! 

Furnace Won’t Ignite: FAQs

Why is my furnace turning on but there’s no heat?

This could be due to a variety of issues, including a problem with the thermostat settings, a dirty air filter, or issues with the furnace’s internal components. If you change the filter and there are still issues, call in an HVAC technician.

Why can’t I get my pilot light to light?

This might be due to a faulty thermocouple, insufficient gas flow, or drafts in the area. Make sure the gas valve is fully open and try relighting it following the manufacturer’s instructions.

Will my furnace kick on without a pilot light?

For furnaces that rely on a pilot light, the furnace will not operate if the pilot light is out. However, newer furnaces use electronic ignition systems and do not require a pilot light to operate.