Furnace systems are complex and have many moving parts. This means that pinpointing a single reason for a furnace problem can be challenging.
Start by checking the power switch directly connected to your furnace (it looks like a light switch). Make sure it is flipped on.
If you smell gas, turn off the furnace, ventilate your home, and contact a professional technician immediately for safety reasons.
A faulty thermostat is often the cause of furnaces not producing any heat. Luckily, you can check several things to see if it’s a simple fix.
First, make sure the thermostat is set to heating mode and that the temperature setting is higher than the current room temperature. This might seem like a no-brainer, but it is actually quite common for the thermostat to be misplaced or for someone in the house to accidentally change the settings.
Next, you can check the vents and registers to ensure that nothing is obstructing them. It’s common for big items like furniture or rugs to block vents and reduce airflow. It’s also possible that the louvers are closed and need to be opened. You can try using your hands or a long wire to open them and restore airflow.
A furnace that turns on but does not produce heat may be low on fuel. If it uses liquid propane or natural gas, it may need to be refilled. It’s also a good idea to check the gas supply line and ensure that it is open. If it’s been shut off for any reason, you can contact your utility company to find out when things will normalize.
Unusual Sounds
Most furnaces produce some noise when they run, and this is normal for a system that ducts warm air throughout the house. However, strange sounds like chirping or banging can signal a problem. If you hear these sounds, turn off the furnace and call an HVAC contractor for help.
A clunking sound can indicate that the blower motor is misaligned, and this issue can cause the fan belt to hit against other parts of the unit as it rotates. Similarly, a knocking noise may point to a cracked heat exchanger or other internal issues that require professional intervention.
The clanking sound of loose screws or panels can also signify that something needs to be tightened. A technician will check for dislodged components and tighten them to resolve the noise and prevent further damage.
Another common issue that leads to unusual furnace sounds is a gas leak or other serious safety concern. These are typically accompanied by obnoxious smells and can put your home at risk of fire or carbon monoxide poisoning. A HVAC technician will perform a safety inspection and address the problem promptly for your safety and comfort.
A rattling sound could indicate a problem with the access hatch, panels, or doors, and an experienced technician will ensure all screws are firmly fixed to reduce the sounds of loose or shifting parts. A loud rattling sound may also indicate a broken capacitor that needs to be replaced. This can be a costly repair, but our technicians can replace the capacitor quickly and efficiently to lower your energy costs and prevent further problems.
Faulty Thermostat
It’s not uncommon for HVAC systems to run into trouble from time to time. However, some problems are more severe than others. Fortunately, there are steps that you can take to troubleshoot your furnace and prevent the need for extensive repairs.
A common problem is a thermostat that won’t turn on. If you switch on the system, but the screen remains dark, this indicates that the electrical wires have failed. These wires transmit signals to the thermostat that tell it when to start a heating cycle and what temperature to set. If the wires have ceased to function, your thermostat will be cut off from your cooling and heating systems, meaning that you won’t have any hot or cold air.
Another possible sign of a malfunctioning thermostat is the presence of strange sounds. If the unit is battery-powered, you can replace the batteries to see if this fixes the issue. Otherwise, you can look at your breaker box and check for tripped breakers or blown fuses that are cutting off the energy supply to the furnace.
Additionally, make sure that your ducts aren’t clogged with dust or debris. If they are, you’ll only be able to get warm or cool air in certain areas of the house. If you think this is the case, consider having your ducts professionally cleaned. In most cases, the heat exchanger will need to be replaced.
Faulty Gas Valve
The gas valve is an important part of the furnace that controls the flow of gas into the heating unit. Occasionally, this component can get clogged or damaged by debris that enters it, inhibiting its function. If you have a gas valve issue, it is critical that an experienced HVAC technician inspects and repairs it as soon as possible to ensure your home is properly heated.
If the gas valve is faulty, it can also cause a gas leak, which poses major health and safety concerns. Leaking gas can spread throughout your house and ignite if it comes into contact with any kind of ignition source like a candle or a flame from cooking. This can cause dangerous fires and explosions in addition to posing a threat to your family’s safety.
If you notice the odor of leaking gas, shut off your furnace immediately and open doors and windows for ventilation. Then, exit your home and call an emergency HVAC team for inspection and repair as soon as possible. Inhaling leaking gas for extended periods of time can lead to respiratory issues and even death.
Faulty Flame Sensor
If you are noticing that your furnace frequently shuts on and off, or if it’s taking a very long time for the pilot light or main burner to ignite after it starts, the problem could be with your flame sensor. This part of the furnace is designed to detect a flame, and when it fails to do so, the system will shut itself down until it can. This can be a major inconvenience, but also an energy waste and safety issue.
A clean flame sensor will make sure that both the pilot and main burners stay lit, and will keep your furnace working as efficiently as possible. The good news is that cleaning a flame sensor is generally an easy DIY repair, and can help you avoid expensive furnace repair bills.
However, it’s important to note that if your flame sensor cannot be cleaned or realigned, it is likely time for a replacement. It’s best to contact a professional for this type of repair as they will have the tools and equipment needed to safely and effectively install the new flame sensor.
Before you do any work on the flame sensor, make sure that you turn off all power to your furnace by switching off the switch next to it or removing the breaker for your furnace in the home’s circuit breaker panel. Then, let the unit cool down for 30 minutes before you start. Next, remove the access panel covering the flame sensor, which is a metal rod that looks like a thin and possibly bent arrow. Then, use emery paper or light-grit sandpaper to gently scrub away the soot and debris from the rod.
Faulty Door Switch
If you have a gas furnace, check that the switch next to your house (which looks like a light switch) is flipped up in the “On” position. Also, make sure the home’s power breaker is in the “On” position, too.
The furnace will only start running when enough energy is supplied to the ignitor, which creates the spark that ignites the gas supply and heats the air. If the ignitor is failing, the furnace will continue to run but will not produce any heat.
A malfunctioning ignitor can cause problems in a variety of ways, including overheating. A damaged ignitor can be easily replaced by a qualified heating repair technician.
Similarly, a damaged flame sensor can prevent the system from operating, often due to soot or dirt build-up on its rod. The flame sensor is an important safety feature that should be inspected routinely to ensure it works properly.
If your furnace is blowing air but producing no heat, start by checking that the thermostat is set to a temperature above the room’s current temperature and the fan switch is in the ON or AUTO position. You can also try turning the fan up a few notches. Finally, you can use an ohmmeter to test your door switch for continuity. Note that this test will damage your ohmmeter, so only do it if you have one at home or have a professional repair service available.