When your furnace is running, the last thing you want to feel is cold air. You know the furnace is running because you hear the fan or blower, but the air it’s blowing isn’t warm. Before calling for help, you can check a few things yourself. You might solve the problem and save the day. If not, you’ll know it’s time to call a pro. Remember to always call for help immediately if you smell gas.
Let’s look at five common reasons a working furnace might stop heating.
1. Thermostat Problems
The furnace often takes the blame when the thermostat is at fault. First, check that you remembered to set the thermostat to the heat setting. If the thermostat is set to “cool” or “fan”, then you will not get warm air. The blower will circulate cool air. Once you have double-checked that the thermostat is in heating mode and set at the correct temperature, you can safely assume that the problem is most likely your furnace.
2. Filthy Air Filter
A dirty filter is a common problem. If dirt covers the air filter, then air cannot flow the way it should. What happens next depends on the type of furnace you own. A gas furnace might simply overheat, turning off the burners as a safety mechanism. Your gas furnace, now off, will not blow any air, and your home will remain cool and unheated. If your furnace is an electric model, it may overheat as it tries to push air through the clogged filters. Once it overheats, the heating elements will shut down, but the blower motor will keep blowing. The air that moves through will be unheated.
So take a moment to check the air filter. If it’s full of dust or just plain filthy, replace it with a new one. Wait a few minutes, and then check to see if the furnace is blowing warm air. Then try to change the filter about every three months to avoid a recurrence of the issue.
3. Faulty Pilot Light or Ignition on Gas Furnace
One thing a gas furnace needs is fuel. If your gas furnace is a modern model, it likely has an ignition switch. If the furnace can’t ignite the fuel, you won’t get heat even if the blower still runs. Older gas furnaces have a pilot light instead of an ignition switch. If the pilot light goes out, the furnace can’t produce heat. Check to see if the pilot light is out. If you don’t know how to relight it, call a professional. For an ignition switch, listen for clicking sounds when the furnace tries to start. Cleaning the igniter can sometimes solve the problem. It’s best to call a pro to deal with this issue.
4. Dirty Flame Sensor on Gas Furnace
A flame sensor is a metal rod located inside a gas furnace. The sensor makes sure the burner’s flame actually lights when the gas turns on. If the sensor is dirty or failing, the furnace might turn off the gas. Even though the gas is off, the blower might continue. Removing and cleaning the flame sensor is a job best left to a professional HVAC technician. If cleaning doesn’t help, then you might need a new sensor.
5. Leaky Ductwork
Maybe your furnace is fine, but leaky ducts are the problem. Large holes, disconnected ducts, or unsealed joints cause warm air to escape before it arrives. Duct blockages can reduce heat delivery, too. If you have access to the ducts, you can check for holes or loose joints. UL-181 rated foil tape is specifically for HVAC ducts, and you can use it to seal leaks.
When to Call an HVAC Technician
Troubleshooting is great, but it doesn’t always lead to a solution. Things like a failing igniter, a bad control board, or a cracked heat exchanger need professional attention. It also helps to have expert knowledge, tools, and parts. An HVAC technician can inspect, test, and safely repair or replace your furnace. We offer routine, yearly HVAC maintenance, which is a good idea to avoid future problems.
Contact the HVAC Professionals
Homeowners in Fort Mill, SC call Arce Heating & AC for their furnace needs. Our HVAC technicians offer heating maintenance, repair, and installation services. Contact Arce Heating & AC for furnace repair when your system starts blowing cold air.
