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Twelve Furnace Repair Issues and How to Fix them

You wouldn’t want to find yourself waking up cold at midnight. It’s one thing if you simply need to pull up the covers or throw an extra blanket on the bed. But it’s an entirely different problem if your furnace is malfunctioning or not functioning at all.

Do you have some DIY-experience? Then you might not need any help to diagnose and repair your furnace. However, it would count wise to use a maintenance checklist for your particular heating system, so you don’t miss anything.

Top 12 Furnace Problems and Ways to Resolve Them

Regardless, if you own a high-efficiency gas furnace or just a traditional gas furnace, understanding how your heating furnace system works is essential. You should know the appliance’s fundamental sequence of operation, so you understand what things to look for when there’s something wrong.

Below is a detailed look at a traditional furnace and useful tips to fix its more common issues. If any of these DIY steps makes you feel somewhat uncomfortable, you should, of course, call for professional furnace repair. Saving a few dollars is not worth the uncertainty or an undesirable occurrence involving the furnace.

1.      Confirm that Your Thermostat is ON

Although it might sound silly, you need to confirm that your thermostat is set on “heat” and is at least 1-degree Celsius above your particular room temperature. Quite frankly, a lot of people make service calls even without confirming this!

Below are a few things you ought to check on your thermostat:

Step 1: Check the thermostat’s battery. You might need to replace the batteries on the thermostat. In case your home’s thermostat unit works on batteries, ensure that you are replacing them at least once a year.

Although thermostats are often wired to the furnace low voltage system, some use batteries. So, how is your thermostat powered? Those that need batteries will sometimes flash a low-battery symbol if they need a change.

Step 2: Open your thermostat and slowly blow any debris or dirt that might have clogged it.

Step 3: Ensure that the time and date are precisely set on programmable or electronic models – the system might be on a timer or schedule.

Step 4: Inspect the breaker. Make sure that you turn the breaker OFF before inspecting the fuse for the furnace.

2.      Furnace Isn’t Generating Heat – Reset the Home Circuit Breaker

Generally speaking, there are numerous minor reasons why this might occur. For starters, check that your thermostat is set to “Heat.” Next, try moving up (or down) the dial a few degrees to find out whether you feel a noticeable difference.

In case there is no outcome, check to see whether a fuse or circuit breaker was blown or tripped.

How to Test Home Circuit Breakers:

In your home’s breaker panel, you can find a circuit that controls the entire furnace. The goal is to see if it’s thrown to the “OFF” position, or if it’s in the center.

–  Manually test your breaker by flipping it back and forth.

–  Ensure that it remains in the “ON” position.

That should reset the breaker. In case this doesn’t work the magic, then you either have a problem with the circuit breaker itself or the wiring in the circuit.

3.      Furnace Isn’t Generating Sufficient Heat – Check & Replace Your Clogged Filter

As aforementioned, it is one thing to have a furnace that strains to generate heat and a whole different issue to have one that has somehow stopped functioning.

Do you have a poor-performing furnace that never heats the house sufficiently? The first thing you ought to do is to confirm that the air filter is new, or at least neat and in good condition.

Check & Replace Your Clogged Filter

It’s a much straightforward but integral part of furnace maintenance. A clogged filter is one of the prevalent causes to have a malfunctioning furnace. What’s more, it is the simplest maintenance chore.

Changing your furnace filter frequently is a quick and easy task, and plays a significant role in improving your home’s inside air quality and protecting HVAC components.

– Locate your filter. Most furnaces contain their filter in the intake. Typically, this usually looks like a grate in a wall, ceiling, or floor. Other filters reside in the actual furnace.

– Check the filter. As a general rule, you may know whether the time has come to replace it by holding it up to a light source. In case no light shines through, then the filter requires to be replaced. A dusty, strange smell from the vents, once the blower is on, is another clear indication that you should replace your furnace filter.

– Change your filter. Ensure that you turn off the furnace. No air should also be coming out. Look at the direction your filter is pointing. Typically, filters are designed to trap materials blown from a certain direction. Setting up your filter upside-down might lower its effectiveness.

Besides, cleaning the dirt that accumulates on your filters will help with the flow of air. So, what happens with a clogged air filter? It means that the air handler needs to work more to make up for the blockage of airflow. Apart from increasing your utility bill, the limited airflow through your cooling & heating system might make your heat exchanger overheat and even shut off too fast.

Filters usually clean the air passing into the furnace, as well as the heated air that’s sent back into the home. A dusty, clogged filter blocks the airflow and ultimately causes pressure and heat to build up in the furnace.

Mostly, newer and more efficient furnaces are vulnerable to the issue and will shut down before a dusty filter brings more problems. In other units, furnaces might continue to operate but with reduced efficiency and less heat output.

4.      Safety Switch on the Furnace Door

In case your furnace is not working, the first step you must take is to look at the safety switch on your furnace door. Typically, a furnace door safety switch primarily prevents the burner and fan from coming on during the access panel’s removal.

Furnaces usually have a safety switch that comes out once the door is removed. If you want the switch to be activated and the furnace to work, the door should be in place!

In case you realize that you ought to set up a brand-new safety switch, here is a step by step instructions on how you could set up one for your Furnace Door.

– Turn off the power

– Prepare the blower door

– Wire your safety switch

– Inspect & test the installation

5.      Maintain a Clean and Unobstructed Area Around Your Furnace

Although this might seem like an obvious thing, homeowners with busy lives sometimes forget to attend to some of their home areas, such as the basement.

Once a basement is cluttered, it might result in the area surrounding that furnace being filled with debris and unnecessary items. Apart from having improved performance, a clean surface will also look much better.

Avoid keeping flammable materials or substances near your furnace. Generally, crowding your furnace might result in unexpected fires, substantial damage to your house, and risk to your family members and pets.

It might seem quite convenient to simply “keep it there” during summertime. However, consider the likelihood that you might well forget any possessions you have left on or close to the furnace. As a result, give the furnace the space it requires to work safely.

What’s more, vacuum and clean frequently around the furnace. Although you might have removed all flammable materials from that area, don’t forget that lint and dirt can accumulate and cause a fire hazard. Besides, an excess amount of lint and dust can also make your filter clogged sooner than expected, demanding more regular replacement.

6.      Check the Burner Flames

In most cases, the failures related to burners originate from contamination. Because of this, you’ll have to inspect your burners and ensure that they’re free from debris. You will need to ensure that you have clean burners and the best way to do this is to check the flames.

Are they even and blue?

If so, your burner is probably clean. In case they are yellow, you most likely have dirty burners. Although a vacuum cleaner is useful when it comes to cleaning your burners, just ensure that you turn off the power and gas before everything else. Another region you ought to clean with your vacuum cleaner is the area around the blower.

Undoubtedly, dust might build up in summer. As a result, you must inspect and clean the furnace burners – especially before the beginning of the colder seasons.

A mixture of soot and condensation can cause burners to work ineffectively and might also cause other furnace issues. The prudent thing is to clean the burner assembly yearly or change it the existing one is in bad condition.

7.      Oil the Furnace Blower Annually

When preparing the furnace for winter, it’s essential to ensure that each component is clean and in good condition.

The furnace blower’s primary role is to take the heat from the furnace and then distribute it all over the house. Extend the life of your furnace by keeping the furnace blower lubricated.

Below is a list of 7 simple steps of how to oil your furnace blower motor:

  1.  Switch the circuit breaker off at the main central panel that provides the furnace’s power.
  2.  Use a screwdriver to detach the screws and remove the furnace’s access panel.
  3. Find the blower motor assembly close to the furnace’s base. Remove the bolts attaching the blower motor to the main assembly of the furnace with a wrench.
  4. Find the set screw on the blower motor housing’s side. Detach the bolts. Then, pull the motor from its housing.
  5. Identify the oil parts on the shaft and motor.
  6. Squeeze 2-3 oil drops into each port.
  7. Activate the furnace. The blower motor will run much better with the new oil.

When it comes to how your heating system works, the furnace blower motor has a significant role. It needs to be oiled once every year and it should not make any strange noises when started.

8.      Look at Your Limit Switch

A poor limit switch might cause the blower to run constantly, and because of this, it will significantly reduce the blower’s lifespan.

Hiring a technician to replace the limit switch will quickly fix that issue.

So, how can you test whether your furnace problem is the thermostat or the limit switch?

If it’s because of a bad high limit switch, the furnace shouldn’t fire. In case the high limit switch trips, the heating/ flame element will soon be turned off and the blower will go on clearing the heat. In fact, the blower will operate until either the limit switch closes, or the system is reset.

Usually, limit switches are closed, and they should fail open. That means that when the temperature gets too high, or they go bad, they open the circuit. In case the circuit is open, you will need to change the limit switch.

9.      Look at Your Pilot Control or Electric Ignition

Gas furnace operation can have electronic control or work with a pilot light, which does away with the need for a constant flame.

A malfunctioning ignition system like the ones in furnaces with a thermocouple might drastically lower the furnace’s ability to efficiently heat the house. Clogs or drafts in your heating system might lead to your pilot light shutting off.

Most newly introduced systems ignite electrically, instead of by standing pilot light.

The action steps that you may take are:

  1.  Turn off the furnace power switch and then back on (the ignition might need to be reset).
  2. Turn off gas and power to the furnace to enable inspection of the heating element. Make sure that you don’t touch the heating element. However, if it looks damaged or cracked, you will have to change the igniter.
  3. With the assistance of the furnace’s manual, check out the steps suggested by the manufacturer to troubleshoot the operation. Just like with the pilot light, you could actually destroy the system and your house if you ignore the steps or safety methods during this task.
  4. Follow the instructions and in case it doesn’t work, contact for service.

10.  Heating or Rapid Cycling Issues

Many causes exist when it comes to a furnace turning on and off too fast. Of course, the first cause might be a worn-out or dirty air filter. In case you haven’t changed it in recent times, try it out – it is an easy and quick fix.

So, when do you call a professional? In case a new filter doesn’t fix the issue, you might be dealing with a more serious situation. Perhaps, there is a problem with the blower motor and belts. They both demand the service of an expert.

11.  Furnace Doesn’t Blow Air

Check out the furnace’s inspection window. Ensure that the blower is debris-free. What’s more, there has to be a flashing light; red or green.

Always confirm with the manual. If the light shows green, it is alright; if red, reach out for service. In case there’s no light, the furnace problem might be with the transformer, furnace control board, the run capacitor, the blower motor, or the thermostat.

12.  The Gas Furnace Blower Runs Constantly

Typically, the blower is situated between the furnace and the return ductwork. Cool air is usually passed by the blower through the heat exchanger and heated before being passed to the plenum and finally sent all over the house by the supply ducts.

More often than not, a continuously running furnace that never shuts off can indicate a required repair. Make sure/ confirm that your thermostat isn’t set to “continuous fan”.

Next, turn down the temperature to see whether this step fixes the issue.

A gas furnace that doesn’t turn off might also be a sign of an issue with a faulty limit control switch. (This might require resetting or replacing).


Hopefully, this article has taught you ways to resolve some of the common furnace issues. Have you experienced any of the above DIY repairs?

Getting your system inspected routinely, and at least as frequent as the manufacturer recommends, may prevent a minor repair issue from deteriorating. Trying out DIY repairs can be affordable and satisfying. However, it’s essential to ensure that you have the relevant skills before trying out any work on your furnace.

In case the tips don’t help you identify or fix issues or if they’re above your skill-level, you might need the services of a reliable furnace repair professional. It’s essential to maintain routine tune-ups and cleaning of your HVAC system.

More about heating and cooling systems

Homeowner Tips For Caring For Your Furnace

Now that winter is here, there is a critical home maintenance task that needs to be cone to help your house stay cozy and warm – and that is to ensure that your furnace is in good working condition.

The furnace is one of your home’s most critical pieces of equipment. It generates warm air to keep your home heated during the coldest months of the year and works as an air conditioner as well to cool your home down during the summer. Fortunately, furnace maintenance often is quite easy.

The following is what you need to know when it comes to caring for your home’s furnace:

Furnace Maintenance That You Can Do Yourself

There is some routine maintenance that you can do on your own to help ensure that your furnace continues to run efficiently and safely.

Inspect and Change Your Air Filters

It is recommended by ENERGY STAR that you check the air filter on your furnace once a month and replace it whenever it looks dirty. If you have a dirty filter in your furnace then it can reduce efficiency and slow down air-flow. If too much dirt and dust build up inside then your furnace might stop working. ENERGY STAR says, at minimum, your filter should at least be changed every three months.

image showing comparison of a clean and dirty furnace filter

Tip: Furnace filters will work the best when they have a snug fit – so be sure to purchase a filter that is the right size to fit your furnace.

Keep Your Vents Clear and Clean

Before turning your heating system on for the winter, take the vent covers off of the ceilings, walls, and floors around your house. Vacuum the covers and duct openings. Small objects (such as toys), pet hair, dust, or even food may collect in there. That can end up blocking air-flow and cause your furnace to have to work harder than it should.

homeowner looking into furnace vent openings

Tip: According to ENERGY STAR, when you seal leaky air ducts using duct sealant or metal tape it can help to improve your heating system’s efficiency.

Get a Carbon Monoxide Detector Installed

Furnaces burn oil or gas to heat your house and therefore generate carbon monoxide, according to the Centers for Disease Control and Prevention. Battery-backup or battery-operated carbon monoxide detectors should be installed on each level of your house to alert you if your furnace starts to leak this odourless, dangerous gas into your house. The detectors should be checked on a regular basis to ensure they are working properly.

carbon monoxide detector

Tip: Change the batteries in your detectors once a year at least. The ending of daylight saving times can be a reminder for when this task is done.

Professional Furnace Maintenance

ENERGY STAR reports that having an annual tune-up conducted by a professional is an essential part of keeping your furnace well-maintained, and it can help to prevent future expensive furnace repairs. A heating contractor can ensure that your thermostat is working properly and that the system is cycling off and on correctly. The professional will normally go through a series of tasks and checks, including the following:

Check the heat exchanger for cracks
Clean the burner
Inspect all of the gas connections
Oil all moving parts
Tighten any loose electrical connections

heating technician working on a thermostat

Tip: According to ENERGY STAR, you should call a contractor before the temperature starts to drop. Otherwise, you might find it hard to get into their busy schedule once winter hits.

After all of the above has been done, listen carefully for signs of trouble whenever your heating system is operating. If your furnace is rattling, squeaking, or making any other strange noises, it could be a sign that your unit needs to be replaced, that the furnace is due for a cleaning, or that a part has come loose. If you notice any strange sounds, call a professional for assistance. We hope you’ve found these homeowner tips for furnace care helpful.

Your furnace is essential to keeping your house comfortable all winter long. Taking care of routine furnace maintenance tasks can help to ensure that your furnace stays in good working condition so that you stay cozy and warm all winter long.

How to Identify and Repair Your Roof

Ice Dams on the Roof

When ice dams are located, you will notice a blackish grey or green clouded over center of the roof. Since the roof has been dripping with water for a lengthy winter, the metal melting into water will also be covered with black ice. You might have to search for some other way to identify the location of the ice dam, like rain or snow.

roof structure with ice dam issue

In a well insulated building, the water in the icicles will melt fairly quickly or freeze into a solid block, giving you the large crack your leak was uncovered. However, there are places where this ice will remain, harbouring water. If that happens, the ice block will slowly (within a couple of days), grow larger with the humidity in the building, still forcing it through the roof sheathing, and eventually freezing. You will likely have to place tarps below the water line on the leak, and paint the roof black or brown in order to hide the drip hole.

These tough, traps will hold the water in place without preventing its infiltration through the roof sheathing. If you are in an older building where the roof leaks are not easy to take care of, a drip-repair does not add much to the cost of the roof, because the roof and water meter are usually on the roof, and there are no water stops above roof vents to prevent you from having air circulation in the building.

Flashing and Channels

Tin channels or flashing are also embedded in the roof sheathing to catch any larger leaks. These can be on the recessed standard channels underneath the sheathing or they may be on smaller duct or outlet ducts. Even when the offset output of the vent is not a problem, it might still cause attic drafts in upper floors.

If you are in an older building where large leaks have been spotted, you may have to retrofit your entire house for additional nail joints along certain channels to provide additional insulation.


The best way to tell if more insulation is what you need is to start by checking the temperature of the shingles. If they are warm and covered by ice, you need to install more layers. Even if you don’t have ice dams, the temperature of the roof sheathing may still be too low for your insulation. In this case, retrofitting the roof or both it and the sheathing is normally necessary. We will also show you a few more tricks for fixing roof leaks and keeping the heat in.

Chimneys and Vents

First, you may encounter leaks in the gable-end vents. These are one of the main causes of chronic attic drafts, especially in upper floor houses. In addition, through the attic mean outdoors air-streams, such as those from bathrooms, melting garden leaves and snow, can cause condensation on gable vents. This can affect the air movement through the roof and lead to bringing hot air back up into the attic, slowing the convection of heat from the home.

Finally, sometimes you find leaks in chimneys and vents, because they are frequently the source of cold air in your home. Besides being an air movement bottleneck it is also a large source of true hot air from adjacent rooms, which can cause drafts in the attic.

Many times this can be addressed by installing the hoses from the home’s gas, electric, water and sewer service to the fireplace or any furnace running in the home. This solves the air re-circulation problem, but is far more costly than just making the HVAC system itself better insulated. If the system is not located close to the room you are trying to heat, there may be other alternatives.

It should be pointed out that all the roof leaks we will talk about here are relatively minor and can usually be fixed with some simple tools. The problem is likely to be more serious when dealing with less than strong reinforcements. If the roof is already pretty deteriorated, there are times that patches can be tricky.