Furnace Won’t Turn On? Troubleshoot Guide

The furnace plays a key role in keeping your house warm and cozy in winter. Sometimes, your furnace won’t turn on when you plug it in or adjust the thermostat. Dealing with such a non-operational furnace seems to be daunting. But in many cases the actual cause of the issue is maintenance. You don’t need to replace the entire system. But you cannot do any fixing unless the issue is identified.

So, if your furnace is not turning on and you are shivering in the cold, just take a deeper look into this guide. Here, you will find all the common reasons when your furnace won’t turn on with their handy solutions. Without further delay, lets’ explore! 

Power Supply Issues (Furnace won’t turn on)

One of the first reasons when your furnace won’t turn on is the power supply. An absolutely new furnace with no power supply cannot start. So, before blaming anything, make sure the power supply to the furnace is On. Sometimes, a specific area experiences power outages and you have no idea about it. Your attempt to start the furnace fails with the conclusion that it has gone faulty. In other cases, a blown fuse or tripped circuit breaker can also cause this trouble.

How to fix?

The first thing you need to do is check your homes’ main power supply. Ensure there is no power outage.

If other electrical devices in your home are working then it rules out the incidence of a power outage. So, your next step should be the inspection of fuse box. Find the fuse box in your house. Visually inspect fuses and check for any signs of burning or tripping. If you find a blown fuse, carefully replace it with a new one. Similarly, look for circuit breakers and trace the ones in ‘Off’ position. Now flip the breaker to the ‘off’ position first and then turn it back ‘on’ for a reset.

Your furnace will start if power supply is restricting it to start.

Thermostat Settings (Furnace won’t turn on)

The thermostat plays a key role in starting your furnace. If your furnace won’t turn on it means the thermostat may have wrong settings.

Basically, the thermostat is the guide to the furnace. It senses the room’s temperature and sends signals to the furnace. Then, the furnace starts or stops depending on your desired settings. If the furnace does not turn on, you must understand that thermostat settings are incorrect. Similarly, some thermostats now have battery batteries. Your furnace will be off if the thermostat battery is low or dead. A broken thermostat can also be the issue.  

How to fix?

It is very clear that setting the thermostat temperature can fix this issue. There is no technical stuff involved. First, you need to set the thermostat temperature to ‘heat’. This sounds very basic but many homeowners make this mistake at this point. They set a temperature that is lower or equal to the room’s current temperature. When you have this setting, the furnace won’t activate because it gets the signal that room is warm enough. You have to avoid it.

Turn the temperature settings a few degrees higher than the current room temperature. This setting will direct furnace to turn to make the space warm. If your thermostat does not work at all, you will need to buy a new one. Check out Our Energy Efficient Thermostat Here.

Pilot Light is out (Furnace won’t turn on)

Pilot light issue are common in traditional gas furnaces. If your furnace that is not turning on is gas operated then you can assume the pilot light has caused the issue.

You can think of the pilot light like an ignition flame. It helps the furnace’s main burner to light up to heat in normal functions. But, in some cases this pilot light goes out and your furnace cannot turn on.

Many factors contribute in the failure of this light. For instance, the gusts of air or persistent drafts in the furnace can block out the pilot light. In some cases the dirt builds up restricting the light to perform its ignition function.

Your furnace can also stop working because of a faulty thermocouple. If you don’t know what it is, the thermocouple is a safety mechanism in gas furnaces. If the flame goes out, the thermocouple shuts off the gas supply to prevent gas buildup. When your thermocouple is faulty, it will be tricked into thinking the pilot is out and shut off the valve, even when the pilot is burning.

How to fix?

After diagnosing the pilot light issue, you can address it with cleaning of the pilot light area. It will remove debris around light and help in ignition. Similarly, inspect the thermocouple to see any signs of breakage, bend or corrosion. You can also call an expert for this technical issue.

Blocked Air Filters (Furnace won’t turn on)

Air filters play a crucial role in the furnace. Their main function is to filter out dust, debris, pet dander and other airborne particles from the air. In this way, filtered air enters the furnace. Over time, these filters block and make it hard for the furnace to draw in the necessary air for combustion. When there is restricted airflow, your furnace cannot easily dissipate heat. As a result, it can overheat.

Then overheating adds to the fuel and keeps your furnace from turning on. See how – overheating furnace has a safety mechanism – it will shut down the unit if it detects excessive temperature. So, your furnace will not turn on despite having all the connections and functioning components.

How to fix?

Fixing blocked air filters is quite easy. Regular inspection and cleaning helps a lot but the cleaning also depends on the type of furnace filters. Two types of filters are commonly found in the furnaces and these include – disposable and reusable filters. Simply change the disposable filters periodically and clean reusable ones with water and mild detergent.

Gas Supply Issues (Furnace won’t turn on)

A gas furnace relies on consistent supply of gas for functioning. No gas means your furnace won’t turn on. Many factors contribute to disrupt this gas supply making your furnace dysfunctional. For instance, the gas valve is in the opposite direction (Off) and you think it is On. In many cases, gas leaks are unnoticeable. Whatever the case is, your furnace will not start and you will have to survive in the cold unless you fix this issue the way described over here.

How to fix?

Fixing gas leaks is necessary not only to make furnace functional but to remain safe from hazards. So, if you are unaware of the gas valve status, simply check near the furnace. You will find a valve there. If not, you can also check the main gas line coming into your home. Make sure the valve is ‘On’. 

If your furnace did not start despite having the gas valve ‘On’ then check for signs of gas leakage. The first immediate indication of a gas leak is the smell. Natural gas has a rotten egg odor so it is quite easy to detect. Once detected, do not turn on any electrical devices and immediately contact to Gas Company to address the leaks.

Faulty Ignition System (Furnace won’t turn on)

Like the pilot light in traditional furnaces, modern furnaces have an ignition system.

This system is the heart of the furnace and is responsible to ignite the gas to produce heat. Sometimes, this ignition system won’t work properly or is damaged to turn on furnace. This failure to start the ignition results in no heating of the furnace.

How to fix?

When your modern furnace does not start despite all efforts then reset the furnace. Resetting electrical devices can do wonders. Simply turn the furnace off, wait a minute and then turn it back on. Now listen for the furnace to attempt ignition. Similarly, look for obvious signs of wear, damage or buildup of debris near the ignition area.

Overloaded Blower Motor (Furnace won’t turn on)

Just like any other electrical appliance, furnaces also have a motor that is a blower motor.

The function of the blower motor is simple. It pushes heated air from the furnace to your house. So, you can call it an important part of the furnace. But, the continuous use of the furnace for a longer period can upset this motor. It gets overloaded and restricts furnace to turn on.  Similarly, dirt, dust or debris can also accumulate inside the furnace causing motor to work harder.

All of these things lead to the following problem: furnace won’t turn on. You can also experience mechanical failures of the motor like worn-out bearings or faulty wiring. These issues put a strain on the motor and lose its ability to perform function. In return, furnace won’t turn on or if start, heated air will not be circulated.

How to fix?

When it comes to fixing an overloaded blower motor, you need to wait and reset. There is also a thermal overload protector in the motors. When the motor becomes overloaded the thermal protector shuts it down to prevent damage. This activity gives time to the motor and furnace to cool down and reset on its own.

Similarly, you can do a physical inspection. But, ensure safety by turning off the power to the furnace. Touch the motor gently. If it feels warm, the motor is overloaded. Also inspect for visible signs of damage or you can call a technician for any repair or replacement. This should fix the issue when your furnace won’t turn on.

Conclusion – Furnace won’t Turn On

A non-functioning furnace is more than just an inconvenience. It can disrupt your entire routine and comfort, especially in the colder months. The good news is that you can fix the problem when your furnace won’t turn on at your home with careful inspection and practical application of the things guided above.

If you are intimidated with fixing your furnace, hire a professional. Find A Pro Near You Here!