Top 5 Furnace Problems and Solutions

Has your furnace stopped working? These top 5 furnace problems and the simple solutions may help to get it working. Click on the interactive photo for details.

Having trouble with your furnace? You’re not alone. Once the cold weather sets in, furnace problems become increasingly common. Thankfully, many issues have easy DIY fixes. The first line of defense: Check to see if your HVAC system has power. The last thing you want is to have a service tech come to your home just to have him or her flip a switch at the breaker. If power is not the issue, there are other glitches you can check for yourself before calling for service.

These solutions work with most furnaces, but, as always, you should check your device’s manual first and make sure you’re not voiding your warranty.

#1 PROBLEM: Thermostat isn’t working

LIKELY CULPRIT: If your heat isn’t coming on at all, the first thing you should do is check the batteries. Change them if necessary, and, while you’re at it, give the thermostat a good dusting inside with a small paintbrush.

If that doesn’t do the trick, check the thermostat’s location. Too much sunlight or proximity to a heat source can cause the readings to be off.

You can also try to reboot it. Keep your thermostat set to heat but turn the temperature down to about 60º. Then, turn the breaker switch off for 30 seconds and turn it back on. Still nothing? Call in an expert.

#2 PROBLEM: Unit not turning on

LIKELY CULPRIT: Check the emergency shutoff switch for the unit. It’s typically mounted outside the room where the furnace is or at the top of the stairs if the unit is in the basement. These can accidentally be switched off and will cut all power to the unit, which stops it from operating.

#3 PROBLEM: Dirty filter

LIKELY CULPRIT: Not swapping out an old filter can cause a host of problems, not to mention driving up your energy bill. To ensure your furnace doesn’t work overtime, change your filter every one to two months. Here’s how: Turn off your furnace, find the filter, remove the old one (and take note of the size), replace it and turn the unit back on.

#4 PROBLEM: Furnace isn’t igniting

LIKELY CULPRIT: Does your furnace click as though it’s about to turn on, but then go silent and never start? If you’ve checked the power, inspected the thermostat and changed the filter, the pilot light or the ignition sensor is likely the problem. To fix it, start by turning off the gas to your furnace. Then, remove the front panel and find the igniter or ignition sensor, which is usually located near the burners. Check to see if it’s dirty. If it is, remove the ignition sensor with a screwdriver and give it a good clean, being careful not to damage it. Then put it back exactly as you found it and replace the panel before turning the gas back on. If you have any hesitation about this project, play it safe and call in the pros.

#5 PROBLEM: Furnace has blown a fuse

LIKELY CULPRIT: If your furnace keeps blowing a fuse when the heat kicks in, it’s most likely an electrical issue. These types of problems can be tricky because there are numerous causes, and messing with electrical wiring is dangerous. To keep you and your family safe, you’ll want to call in the pros. They’ll look to see if there are any loose wires or water contact, as well as double-check that the fuse size is correct and the transformer hasn’t failed.

While many common furnace issues can be fixed without calling in the professionals, it’s important to have your furnace professionally serviced once a year, especially if you’re not comfortable performing some of the necessary maintenance tasks.

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