We all claim to love the winter with the festivities and holidays until it’s time to deal with the cold. Sadly, the four walls of your apartment may not be enough to protect you from the chilly clutches of the winter season.
Fortunately, you have your furnace standing guard and providing the much-needed heat shield from the freezing temperature. Well, that’s until the furnace gets tired and kicks out.
Furnaces kicking out when you seem to need them the most is a common problem you don’t ever want to encounter. However, a furnace doesn’t simply break down on a whim.
The inability of your heating system to continue doing its job effectively is most probably due to your neglect. However, we’re not here to point fingers or say who did or didn’t do what.
Complaining won’t pinpoint or fix the problem with your furnace. Then again, you won’t always be able to call the technicians at a moment’s notice when your heating system suddenly breaks down.
As such, you need to at least be able to identify and fix some common problems that hinder the efficient running of your furnace. So, this post aims to show you the best way to fix your furnace problems by yourself.
- 1. Common Furnace Problems, Possible Causes and Solutions to Them
- 2. Do Regular Furnace Maintenance
- 3. Final Thoughts
Common Furnace Problems, Possible Causes and Solutions to Them
Having a furnace in top working condition can save you stress, embarrassment and money. Needless to say, you should endeavour to do the regular maintenance of your furnace. That way, you can avoid dealing with problems popping up when you least expect them.
But then again, problems will eventually pop up, and you must be prepared to counter them. Below are some of the common furnace issues that may suddenly pop up and how to fix them.
1. Furnace Not Producing Sufficient Heat
What’s the point of having a furnace that can’t heat up properly? You bought the heating system to bring up the temperature in your living area when things get cold. The unit’s basic functionality is to make you comfortable and protect you from the cold outside.
Understandably, you’ll be upset when the unit can’t do its primary job effectively. Below are some possible causes why your furnace is not hot enough.
Possible Cause – Clogged Filters
Your furnace may not be functioning efficiently due to blockages to the air filters. Dirty filters restrict airflow in and out of the unit. The restriction to the airflow makes it difficult for the HVAC system to distribute heat efficiently.
This problem is more common in convection furnaces. That’s because convection units heat the environment based on the principles of forced air and convection currents.
When the heater takes in air, it passes through the filter, which prevents the debris carried in the air from getting into the unit. But when the filter has dirt clogging it up, it can prevent air entry into the furnace. With an insufficient supply of air in the furnace, the unit will be blowing cold air into the environment per cycle.
You can easily take care of this problem by replacing the air filters on your furnace. Air filter replacement is a standard maintenance procedure. So you won’t experience this issue if you do regular maintenance on your HVAC system.
Possible Cause – Thermostat Not Set to Heat/Malfunctioning
It’s quite possible that there’s nothing wrong with your furnace, and it’s not working because you haven’t set it to work. That’s what happens when you forget to set your thermostat to heat. You’ll find out that your furnace is not working even though it’s on.
So, before you panic, check and ensure the thermostat is set to produce heat. Even if you’re sure you left it on, someone may have put it off while you’re not around.
If the problem persists even though the thermostat is on, you want to check if there’s no problem with the thermostat. The thermostat batteries may be dead, or there’s a fault with the thermostat.
You can know if there’s an issue with the thermostat by checking the fan. If the fan is constantly running and the unit is still not producing heat, something is probably wrong with the thermostat.
Depending on the nature of the problem, you may have to replace your furnace thermostat. If the issue is with the batteries, you can get new ones to replace the dead batteries. However, if the thermostat is broken, you should call in furnace repair technicians to help you with repairing or replacing it.
Several things may be responsible for your furnace not heating up properly. You may end up causing more damage to the unit if you continue to mess with its components. However, the two issues mentioned above are the culprits in most cases.
Nonetheless, if you experience this common furnace problem and attempt all the suggested solutions without success, call for professional help.

2. Furnace Doesn’t Receive Power
It’s common knowledge no electrical appliance can work without receiving power from an electrical outlet. So, for your furnace to work, you need to plug it into a power source. But what happens when you connect the heater, and it refuses to power on?
Then it’s most probably not receiving power and can’t work. So what may be the issue preventing your heating system from receiving power?
Possible Cause – Broken Power Cable
Most people don’t suspect the power cables when their electrical appliances suddenly stop working. So you may be panicking that your furnace is broken whereas the fault is with the power cable.
Needless to say, a broken power cable won’t transfer the needed currents into the unit. So, there’s no chance your HVAC system will work as long as you’re still using the faulty cable.
The obvious solution to this problem is to replace the power cable. However, before doing that, try cleaning the cable port and ensure everything is in order before putting in the new cable.
Possible Cause- Tripped Circuit Breaker
Another common issue that may be responsible for your furnace not powering on may be a fault in the circuit breaker. The circuit breaker is an essential part of the electrical panel of your unit.
Of course, you don’t have to worry about this if your heating system uses other fuel sources. But if it doesn’t, you should check out the circuit breaker on your furnace before trying other things.
After making sure your furnace is well connected to a power outlet and switched on, check to see if the circuit breaker is alright.
If the circuit breaker switch is OFF, flip it ON. Doing that should solve the problem.
If the switch is already in the ON position, flip it off and back on. The tripped circuit breaker may have been a fluke if it stays ON. So, you don’t have to worry about it.
If the circuit breaker trips and goes back to the off position again, there might be a problem with the breaker or the wiring. In either case, you shouldn’t attempt to fix it yourself. Let the professional furnace repair services handle it for you.
3. Pilot Light and Ignition Issues
If you have an old model furnace, one of the common problems you may encounter with it will be with the pilot light. The pilot light may keep flickering off due to a clogged pilot orifice, low flame setting or a defective safety switch.
You can relight your furnace’s pilot light, following the manufacturer’s instructions. However, if it goes out again, try cleaning the pilot light orifice and increasing the flame setting.
Be sure the flame is burning blue. If it isn’t, it may be due to insufficient oxygen. Clean out the intake valve to allow a better flow of oxygen.
4. Faulty Electric Ignition
Electric ignitions are the equivalents of pilot lights on electrical furnaces. So, they don’t use naked flames as with the pilot lights. Nonetheless, they’re also prone to several problems. For instance, they may suddenly start producing smaller levels of heat.
There may also be more irregular heat cycles, or the blower may become overactive. These problems often happen because the igniter becomes too old, a faulty limit switch, or power surges.
Most of these issues will require the expertise of a qualified professional to solve. However, you may also try some easy fixes for your furnace before calling the technicians.
First, you should check the circuit breakers to ensure they’re functioning correctly. After that, check the wiring to the ignitor to make sure there are no disconnections that may result in short-circuiting.
Also, turn off your thermostat while the device is powered on, then put off the device. Wait for 10 minutes, power the unit back ON, and put the ignition switch ON.
Lastly, you may also check the furnace filters and try replacing them. If, after doing all these, the ignition switch is still malfunctioning, you can then call the professionals.
Related Article: What is the Most Efficient Way to Run Your Furnace?
5. Unpleasant Smells From the Furnace
Another common problem you may encounter when using your furnace is dealing with disgusting odour coming from the unit. You may perceive the smell of rotten eggs coming from the areas around your furnace.
The stench indicates a more significant issue that requires prompt response to prevent further damage. Usually, any of the following factors can be the reason for the bad smell.
Pipe Defects/Gas Leakage
In most cases, the primary reason for the bad smell you perceive from your gas furnace is gas leakage. Generally, gas leaks smell like sulphur or rotten eggs—the foul smell results from the mixture of methanethiol and natural gas, which fuels the furnace.
Whenever you perceive such a smell, you should take prompt action to prevent further leakage. You also want to remove all flammable items from the area and attempt to contain the situation.
Start by turning off the gas valve and opening all the windows in the apartment. After that, get out of the house. Then, contact a professional gas service and furnace repair company to care for the mess.

Cracked Heat Exchangers
Sometimes, a fault with the furnace’s heat exchangers may cause an unpleasant smell. Cracks can affect the furnace’s efficiency, causing dangerous carbon monoxide to seep into the house from the furnace.
You also want to look out for soot build-up inside your furnace and water pools around the unit. These are some of the common furnace repair issues and signs of a malfunctioning heat exchanger.
If you suspect cracks on your furnace’s heat exchanger, there’s very little you can do to repair it yourself. Instead, let the professionals handle it while you take measures to reduce the harmful effects of carbon monoxide.
6. Blower Running Continuously
The blower of your convection furnace is never supposed to run continuously. It should stop running once the thermostat gets the perfect temperature level. Below are some possible reasons your furnace blower is running nonstop
Possible Cause – Faulty Limit Switch
The limit switch is often the culprit when you can’t get the blower on your furnace to stop. The limit switch is the mechanism responsible for turning the furnace on or off, depending on the unit’s internal temperature. In other words, it’s also responsible for starting and stopping the blower.
You probably won’t be able to fix the limit switch yourself; you should leave it to qualified technicians. But if you’re handy and have adequate knowledge of how to repair a faulty furnace, you can try it.
7. Weird and Loud Noises
Many things can be responsible for the strange loud noises coming from your furnace. But what they all have in common is that the sounds are often annoying, and they all indicate that something’s wrong.
A loud buzzing noise from the furnace when you power it up may be due to blockages in the chamber. Blockages in the chamber occur because there’s oil or soot build-up, resulting in a delayed ignition.
On the other hand, rattling sounds or vibrations may occur when you have loose ducts or an unstable furnace. So, whenever you notice noise coming from your furnace, try tightening the screws on the ducts. Also, add some padding underneath the unit to provide a more stable base.
Whistling noises can result from leaks in ducts or a dirty filter. First, replace the clogged filter in the furnace and see if that stops the whistling sound. If that doesn’t work, check for leakages and fix them.
Do Regular Furnace Maintenance
You can prevent many common furnace problems if you regularly maintain your heating system. Doing normal restorative activities on your HVAC unit enables you to discover problems early and fix them before they cause the unit to break down.
Essentially, regular maintenance helps you easily avoid problems resulting from clogged filters, unstable pilot lights and malfunctioning blower fans. These components are the main areas technicians pay attention to during regular maintenance sessions.
Furthermore, you can expect the technicians to replace cracked heat exchangers and fix general problems with the furnace during regular maintenance.
Not only that, they’ll discover potential leakage points and plug them up. Overall, you can improve the lifespan of your HVAC system and save money in the long run by doing proper maintenance.
Ideally, you should schedule maintenance service for your furnace at the end of every summer in preparation for the fall. Doing this is not only crucial to improving the lifespan of your heating unit.
It will make sure the system is ready for the upcoming cold weather. So, you can avoid many potential problems or embarrassing situations in the coming winter by conducting regular maintenance.
Related Article: How Much does it Cost to Repair a Furnace in Toronto
Final Thoughts
So what do you need to do when your furnace suddenly stops working? For starters, don’t panic. Try to identify the problem and see if it falls among the common furnace problems discussed here.
Once you’re sure of the issue, proceed to fix it or call the professionals depending on the situation. At least, you should be able to replace air filters and clean up the system without any help.
You can call us if you need professional help fixing the problem with your furnace. ALP Heating offers same-day furnace repair services for residents in Vaughan and the rest of the GTA. Get in touch with us today!