If you turn on your heater on the first cold night of the season, only to discover that it’s blowing cold air, you have every right to be concerned. It’s even worse if your heating system fails when you have a home full of children, grandchildren or other guests, who might have trouble spending time at your home because it’s so cold.
Thankfully, there are some things you can try to troubleshoot furnace issues. There are also some preventative steps you can take to reduce the chance of your heater malfunctioning at the worst possible time or creating a larger and possibly dangerous issue.
Whether a furnace issue is something you can fix on your own depends on the root cause. Many complex heating matters, such as problems with the burner, flame sensor, oil tank, thermocouple, gas valve, ignition, oil filter, duct or computerized controls, require the help of a professional.
However, homeowners can often troubleshoot and resolve some simple heating and cooling system problems without assistance.
Fan Setting and Other Thermostat Issues
To start with the simplest of fixes, if the thermostat’s fan is set to ON, then the blower will run all the time—no matter whether the furnace is heating air at the time. To check if your fan setting is the culprit of your cold air issue, change the thermostat setting to AUTO. When it’s set on AUTO, the furnace’s blower should only run when the unit is heating air.
Another possibility is that your thermostat’s batteries are low. If this is the case, changing the batteries should solve your issue.
Clogged Condensate Line
Dirt, ice, mold, dust or other debris might clog the condensate line, causing the heating and cooling system to shut down. If you think ice might be the issue, you can try wrapping the line with insulation and heat tape. For other types of clogs, you might be able to clear the line with a wet/dry vac. If you want to try this, first turn off your heater at the thermostat and breaker. Next, connect the hose of the vacuum to the exit point of the condensate pipe using an airtight connection and then suck out any debris clogging the line.
Alternately, a heating and cooling professional can check the condensate line, condensate pump and the rest of your furnace for you, so you don’t have to risk causing a larger issue while trying to unclog the line.
Pilot Light Isn’t Lit
If your unit has a pilot light and it is not lit, then the furnace won’t ignite. If you feel comfortable reigniting the pilot light by yourself, there are some basic steps you can take to resolve this issue.
Before you try relighting the pilot, make sure to turn the furnace thermostat to the OFF setting. Next, locate the reset switch in the unit’s pilot light assembly and turn the knob to the OFF position.
After about five minutes, press the knob to restart the flow of gas. While you press the knob down, hold the flame of a lighter in the pilot light opening until it relights. Then, turn the knob to the ON position. If the furnace now ignites, then you can turn the furnace thermostat back on, and the furnace should start blowing hot air again.
If this sounds like more work than you want to take on, or if you worry about dealing with heat and electricity, the best way to quickly resolve these issues and more complicated problems is to work with a professional who has extensive experience with heating and cooling systems. These licensed technicians can fix your current problem, plus they can also check the unit for any other issues.
Some furnace issues that appear to be simple are actually symptoms of more significant problems. These are usually difficult for homeowners to recognize. However, a heating and cooling professional can help ensure that the original problem doesn’t grow into a much larger issue that might damage your heating system or cause a house fire or other disaster.
Even if your furnace seems to be working properly, it’s still a good idea to have a professional check the unit at least once a year. With regular maintenance, you can prolong the life of your system and reduce the likelihood that a problem will leave you in the cold. Additionally, a specialist can locate and fix heating and cooling issues that might at first seem small, before they turn into costly catastrophes.
Now that we have covered the most common reasons heaters might not be working, we’ll move on to exploring other possible reasons that your furnace is blowing cold air, including that your unit could be overheating and shutting off.
Why Is My Furnace Overheating?
If you go to check on your heater and find that your unit smells like it’s burning or it’s making an odd noise, your furnace could be overheating, which might cause it to stop heating air to your desired temperature. Some common problems that can lead to your furnace overheating include a dirty or clogged air filter, closed air registers and a dirty blower wheel.
Dirty Or Clogged Air Filters
Dirty filters can cause a wide range of issues in heating and cooling systems. If the furnace’s filter is clogged, it can block air from flowing to the heat exchanger, causing the furnace to overheat and automatically shut off. Most professionals recommend checking the filter at least once a month, since it can easily get dirty from dust, pet hair, pollen and many other types of debris. Filters generally need replacing around every 90 days, although this depends on the needs of your specific household and the type of filter you’re using. If you have a washable air filter, it is recommended that you clean it about once every three months.
Less expensive air filters often need changing monthly, while higher quality filters might last as long as six months. Additionally, you might need to change your filters more frequently if you suffer from asthma or allergies, you have young children in the home, you run your furnace often or you have pets.
Before trying to check the air filter, ensure the furnace thermostat is in the OFF setting. Next, locate the filter, which is typically next to the blower in the furnace assembly. If the filter is dirty, replace it with a clean filter as soon as possible. Once you turn the thermostat back on, the furnace should resume blowing hot air.
Closed Air Vents
Make sure air vents and grilles are open and are not blocked by things like bird nests, leaves or dirt. Otherwise, the flow of air through your system can become restricted, causing the furnace to overheat.
Dirty Blower Wheel
If the wheel or other furnace components are dirty, the unit’s heat exchanger may not be able to expel heat adequately, causing it to overheat. The best way to prevent this from happening is to regularly change your air filter. A licensed professional can help clean or replace these parts as needed.
Even well-maintained furnaces have a limited lifetime and might start to overheat as they get older. Nonetheless, if you properly maintain your furnace and components like the fan blower and motor, then the unit can usually last around 15 to 25 years.
Otherwise, without regular maintenance, furnace equipment typically deteriorates early, malfunctions and might cause overheating. In addition to helping you with all needed heating and cooling repairs, a licensed specialist can maintain your unit, help prevent overheating and help you get as many years out of your furnace as possible.
Another common problem homeowners have with their heating system is that they find it shuts off prematurely.
Why Does My Furnace Keep Shutting Off?
If your furnace keeps turning off, it’s critical to thoroughly inspect the system to determine the cause. These devices often have safety features that force the unit to shut down in the midst of a hazardous and possibly deadly situation.
Furnaces sometimes turn themselves off because of simple issues or equipment errors, but other times, a furnace shutting down is an early sign of a significant or even dangerous problem. There are two safety features that could force your furnace to switch off:
- High limit switch. This is a safety feature that switches your furnace off if it gets too hot. This most often happens if your air filter is clogged or the flue is blocked. A less common reason is when your blower motor, which typically helps circulate air around the house, breaks or turns off for some reason.
- Flue limit switch. This secondary safety feature will shut your furnace down if the flue is obstructed by something like branches or other debris. It will also turn off if air isn’t properly flowing out of the exhaust flue. Without proper airflow, gas might build up inside the furnace, which could lead to an explosion. This can happen if the induced draft motor isn’t working, which means it isn’t removing leaked or other built-up gas from the furnace.
Another common reason that a furnace might shut off is called short cycling. This is when the heater turns on for a brief period and then turns off early in the cycle, before your home has reached the desired temperature. If the furnace does this repeatedly, it can overheat and cause permanent damage to the motor.
Furnace short cycling often happens because of a dirty flame sensor or a malfunction with the thermostat. If the thermostat is faulty or if it’s mounted in the wrong location in your space, then it might not signal an accurate temperature of your home.
Another common cause of short cycling is restricted airflow through the furnace due to issues like closed heat grates, a dirty blower wheel, blocked exhaust vents or a clogged air filter. Additionally, you may be struggling with a furnace that won’t stay on if your heating and cooling system is too big for your home, which can cause uneven heat distribution in a room.
Unfortunately, there can be a lot of trial and error when it comes to homeowners trying to diagnose these issues. In most cases, your best bet when it comes to heating and cooling repair is to contact a licensed specialist.
ABC Can Keep Your Home Comfortably Warm
There are many things that can go wrong with a furnace and, without proper expertise, you can end up damaging your unit or injuring yourself trying to resolve them. Instead of trying to learn the complexities of your heater while you and your family members are chilly in your home, contact ABC Home & Commercial Services. Our highly-trained specialists can repairs to your heating and cooling system and are available 24/7 for emergency services.