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November 12, 2020
6 min read time

Common Winter Heating Problems and How to Fix Them

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In the dead of winter, the last thing you want is a malfunctioning furnace or heater. However, while you eventually need to replace your heaters and furnace at one point or another, it is reassuring to know that some heating issues can be easily fixed without purchasing a whole new system.  Following routine heating maintenance can also go a long way towards ensuring your furnace or heater does not malfunction when you least expect it. Malfunctioning of your heater can be attributed to various reasons. It is important to remember that heaters and furnaces have many moving parts and require proper maintenance.

The Most Prevalent Heater Problems &

How You Can Fix Them

Problem: Your heater is blowing cold air

If your heater is blowing out cold air, checking your thermostat, and ensuring it's the correct temperature is the first thing you should do. Also, you need to check if it's set to "auto" and not "fan on" otherwise, the fan will just continue to run without blowing any heat. If you've checked and verified that your thermostat is set right, the problem might be caused by something else. For instance:

Leaky ductwork

This is virtually an invisible problem but it can cause you a significant amount of money if it's not resolved in a timely manner. If you are up to the challenge, you can check your attic or crawl space and check for leaks. You can do this by walking alongside your ductwork and checking for any blowing air. You can also bring a stick of lit incense with you and hold it near your ducts. If you see a movement in the smoke, it is a clear indication that you have a leak in that specific spot. Once you find out where the leaks are, seal them off and insulate your ducts accordingly.

Pilot light issues

Examine your furnace pilot and make sure it is lit. If it doesn't light, check if gas is flowing accordingly. Check the gas valve and ensure that it is on. If the gas valve is on but the pilot light is still not lighting, you'll need a professional's help to resolve the matter.

Dirty air filter

Air filters can become very dirty over time and will need cleaning or replacement. Otherwise, debris and dirt can hinder the furnace from functioning accordingly and cause it to blow cold air. If you suspect that your filter is the problem, fix it and see if it resolves the issue.

Lack of fuel

Regardless if you have an electric, gas, or oil furnace, your system needs fuel to function correctly. If you're low on fuel, expect that your heater won't work as well as it should. If you find out that any of the issues mentioned above does not cause the problem, it would be best to get in touch with an HVAC professional to examine the heating system more thoroughly.


Problem: Some parts of the house are not heating

If your heater is not distributing heat evenly throughout your home, it can be the result of two things: inadequate ductwork and dirty air filters. Check your air filters first for debris and dust and change them when needed. If your air filters are clean, or if you have replaced them and the issue is still not resolved, you might need to check for leaks in the ducts. If you find that your ducts require additional work, get in touch with an HVAC professional.


Problem: Heater won't shut off

If your furnace does not stop running or blowing hot air, you must check your thermostat first if it's set to "auto" and not "on." Setting the furnace to "auto" is essential, so it will automatically shut off as soon as it reaches a specific temperature.

If your heating doesn't stop running, there are two possible issues:

  • The thermostat is miswired or broken
  • The furnace blower is broken

Check the wires of the thermostat and make sure everything is plugged in properly. From there, you can reset your thermostat to factory settings and try rerunning the system. If the issue is still not resolved, consider replacing your thermostat. If you replace your thermostat and the furnace continues to run, the problem can be the result of a blower issue. In cases like this, it is recommended that you get in touch with a trusted heating professional to have the problem checked.


Problem: Heater will not light/does not stay lit

If you have a new furnace, it is possible that it does not have a pilot light and most likely uses electronic ignition. Modern systems have a flame system to ensure gas does not flow when the heater is not on.

It is also possible that the sensors are dirty and might need replacement, so it would be best to check your furnace when you inspect your furnace. The good thing is cleaning and replacing the sensors is something you can easily do on your own.


Problem: There is mold in your furnace

Often, moisture buildup is the result of inadequate ductwork or poor insulation. It also creates a perfect environment where mold can grow. If mold grows in your furnace, you need to hire a professional to get rid of the molds and ensure they won't grow again in the future. Preventing mold from growing often involves making sure the crawl space and ducts are properly sealed and insulated, so moisture accumulation no longer occurs in the future. It is also a good idea to have an HVAC specialist clean your ducts every few years as preventive maintenance.


Problem: Furnace is short cycling

Short cycling occurs when the furnace turns on and turns off rapidly. Short cycling can cause only certain areas to warm up. Other possible causes of short cycling include:

  • Thermostat placement
  • Oversized unit
  • Dirty filter
  • Thermostat fault

Problem: Fan is not working

If your fan's furnace is not functioning accordingly, check your thermostat and make sure it is set correctly. If the thermostat is set accordingly, check if the air filter is not dirty and that airflow is not restricted. If the air filters are filthy, the fan might stop working altogether. If the problem is still not resolved, check the circuit breakers and ensure they are on. If turning the circuit breakers does not resolve the issue, it would be best to check with an HVAC professional as you might have a more complicated problem on your hands.


Problem: Heater smells like burning

If your heating is smoking or gives out a burnt smell, it can be a telltale sign that something is wrong. If the furnace smells like it is burning, unplug and shut it off immediately as leaving it on can be potentially hazardous. However, an unpleasant smell can also be brought about by dust buildup in the furnace or a dirty air filter.

After unplugging your heater, inspect the system for blockage and dust and clean it accordingly. You may also want to clean and replace your air filters for good measure. If the problem persists, check with a professional so they can determine if there's a blockage in the chimney or if the electrical components need fixing.

Final Thoughts

At times, the effort and cost of repairing your furnace or heater are not worth it, and you might be better off replacing them altogether. It would be best to consult a professional in complex cases, so you'll know which option is right for you.

Guest Author: Sara Olsen
Emergency Air Heating and Cooling

Sara Olsen is the Content Marketing Manager of Emergency Air, Arizona’s premier HVAC repair and service company with NATE-certified technicians and the best HVAC service in the quickest time. When not writing articles, she makes the most of her time with her family and gives back to the community.

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