The Complete How to…guide to common furnace repair problems

Oct 29, 2022

The Complete How to…guide to common furnace repair problems

A guidebook for Furnace Repair Problems

Furnaces are subjected to a lot of wear and tear to keep you warm during the cold months! However, several factors can cause a furnace to stop working, including dirty filters, frequent cycling, and age. In many instances, you can repair these problems by yourself by knowing how your furnace functions and the usual issues you are likely to encounter.

Before you call in a furnace repair company, go through the below troubleshooting tasks to see if you can uncover the problem yourself.

1. The Furnace does not switch on:

Make sure that the furnace switch has been turned on. We know how ridiculous this sounds. But if you have been woken up by the cold, rechecking your heater to ensure that it is on “heat” and the temperature selected is at least five to six degrees higher than your room temperature will probably fix your issue.

If this does not fix the issue, confirm if the thermostat batteries have died and need replacement. The other problem could be because the air filters are dirty. It is advised to replace your air filters frequently to avoid dust from clogging your unit. When your filter is not allowing any airflow, it might cause the furnace to shut down.

If the furnace keeps turning on and off, it might be a short cycle caused by a lack of airflow into the device, causing overheating. The device will turn off after being on for a few minutes. Check the air filter and replacing it might solve the issue. If it does not, it might be time to call in an HVAC expert.

2. The Furnace is not producing enough heat:

There can be multiple reasons as to why your furnace has stopped doing its job. One of them could be obstructed airflow or dirty or misaligned gas burners. In some cases, airflow is obstructed by a dirty furnace air filter. If your filter is clogged with dirt, change it. Replace your filter habitually as it refines the condition of the air inside.

Sometimes, your furnace is running but your rooms aren’t getting the proper heat or airflow. Inspect your entire home for all the supply and return grills. They should all be fully opened and unobstructed.

Make sure there are no rugs, furniture, or anything else restricting the flow of air. Not only will blocked vents and registers affect your comfort, but they can also lead to duct leaks due to excessive air pressure and premature HVAC repairs and breakdowns. Closing off vents and registers in unused rooms is NOT a good idea. You won’t save any extra money and will end up causing more problems for your heating system.

If the above measures don’t solve the problem, have a technician come out to clean/adjust the burners and make sure airflow to the combustion air chamber isn’t obstructed.

3. Heater/ Furnace making too much Noise while Operating:

Most heaters make noise as they operate. However, it is essential to pay attention to the noise your heater is making. Some noise could be a sign that something is wrong. For example, a high-pitched noise may indicate shaft bearings need oiling or that the blower belt is slipping; a low-pitched sound can mean that the pilot light is poorly adjusted or that the gas burners are dirty.

To troubleshoot, try oiling blower motor lubrication ports and checking for proper belt tension and that the belt is not frayed. You can also try adjusting the pilot light and having a furnace service technician clean or adjust your gas burners.

In many cases, troubleshooting and furnace repairs will require the services of an HVAC systems professional. Even if your gas furnace seems to be operating fine now, it’s important to schedule an annual heating tune-up to ensure that it will continue to function properly throughout the entire cold season.

4. Water/Gas Leak from Furnace:

Common reasons for water coming from your furnace include condensation leaks, humidifier leaks, plumbing leaks, and clogged internal draining systems. If you notice a leak, you need to call a professional to inspect and fix the problem quickly.

While you are waiting for a professional to come and inspect the issue, shut the unit down and clean up the water (unless you notice signs of an electrical problem, like sparks or a buzzing noise —it is dangerous to be near water when there are electrical issues).

Even if you can’t get in there, try and determine where the water is coming from, while standing a safe distance away. That way you get a head start on determining what the technician will need to do.

If you suspect a gas leak, and the odour is strong, you should immediately leave your home and contact your gas utility company. A gas leak will affect the efficient operation of your furnace. But more importantly, it can be a serious health hazard to you and your family.

5. The Furnace Blower won’t turn off:

The blower, whose function is to gather heat from the furnace, send it to the heat exchanger for warming up, and spread it everywhere in the house, is supposed to turn off after some time. Which is why a blower that keeps on running without breaks is a sign that maintenance is required?

To solve the problem, you should: first, check if the fan is set to run continuously. Fix this by changing the thermostat setting from ‘Auto’ to ‘On.’ Also, try turning the temperature down to see if the problem gets fixed. The other thing would be that the fan limit control switch is faulty and needs to be changed. Sometimes, the thermostat might be worn out and needs to be replaced to fix this problem. Call for a technician to fix the problem.


You can avoid all these problems by making sure that your system is inspected regularly, as this will prevent even minor repairs from becoming huge issues. Try to at least clean up and examine your furnace as often as the developer recommends. In the event that replacing the filter or checking the above issues don’t solve the problem, call a furnace repair technician because there could be some serious problem that needs fixing by a professional .