What to Check When Your Furnace Won’t Turn On
You rely on your furnace to keep your home warm and cozy throughout the winter season. But what happens when it simply won’t turn on? Before you panic or start calling emergency HVAC services right away, take a few moments to perform some basic troubleshooting.
At The Lee Thompson Company, we understand the frustration that a non-functioning furnace can cause. That is why we offer prompt furnace repair services and installs using only high-quality products, such as American Standard, Lennox, and Mitsubishi. Our services are also backed by The Lee Guarantee.
From a clogged filter to incorrect thermostat settings, there are many reasons why a furnace may suddenly stop working. Understanding what to check and when to call in a professional can save you time and money, and prevent costly mistakes. Here are some things to check when your furnace won’t turn on.
Thermostat
The thermostat is essentially the brain of your heating system and therefore should be the first place you check when your furnace stops working. Start by checking if your thermostat is set to “heat” and is not in the “off” or “cool” positions. Thermostat settings can be accidentally changed, especially if you have young children in the home.
Next, check that the thermostat is set to a temperature high enough to trigger the furnace to turn on. For the heating system to cycle on, the thermostat must be set to a temperature higher than the current room temperature. If it’s set too low, your furnace won’t get the signal to turn on.
Finally, inspect the thermostat for loose or damaged wiring. Carefully remove the thermostat cover and look for any frayed or disconnected wires. If you notice disconnected or damaged wires, call in an HVAC professional to repair the wires. Don’t touch disconnected or damaged wires as they could cause an electrical shock.
Power Supply
Before diving into more complex troubleshooting tasks, ensure that the furnace is getting the power it needs to operate properly. Begin by checking that the furnace is turned on. Many modern furnaces have a power switch located nearby. This power switch will often resemble a standard light switch.
If the power switch is in the “on” position, check the fuse box or circuit breaker. A blown fuse or tripped breaker could be the culprit. Locate the furnace’s designated circuit breaker. Reset the breaker if it’s been tripped or replace the blown fuse if necessary.
While examining the furnace, take the time to inspect the system for visible damage. Look for frayed wires, damaged electrical cords, or loose connections. If you notice any of these types of issues, turn off the power to the furnace and call in an HVAC professional to avoid potential safety hazards.
There may be instances where a furnace requires hefty repairs or replacement of parts to restore function. If this happens, you may be worried about how you’ll pay for these services. At The Lee Thompson Co., we offer multiple payment options for your convenience, as well as financing options available upon credit approval.
Gas Supply
One reason why a furnace may not turn on is that it isn’t receiving fuel. Verify that the gas valve is open. You can typically locate the gas valve near your furnace. Check that it’s in the “open” position, which usually means that it’s aligned parallel to the gas line. If it’s closed, your furnace won’t receive the fuel it needs to operate.
Next, check for potential gas leaks. If you smell gas, which usually presents with a rotten egg odor, turn off the furnace immediately and avoid using any electric devices or open flames. You’ll also want to evacuate your home until a professional has cleared you to reenter.
If you find that the gas valve is open, but your furnace still won’t ignite, there could be a supply issue with your utility provider. There are several reasons why your gas supply may be turned off, such as lack of payment. Also, confirm with your utility provider that there are no outages or disruptions in your area.
Air Filter
A dirty or clogged air filter can prevent your furnace from operating efficiently, and in some cases, at all. Locate the air filter, which is typically found in the blower compartment, return air duct, or near the furnace intake. After removing the filter from the heating system, check it for dirt, dust, and debris buildup.
If you discover that the air filter is extremely dirty or clogged with debris, clean the filter or replace it with a new one. Disposable filters should be replaced with a new filter that matches the size and specifications recommended by the furnace manual. If the filter is reusable, wash it and allow it to dry completely before reinstalling it.
Dirty air filters not only strain your furnace but can also reduce your indoor air quality. To avoid future issues, aim to replace or clean the filter about every one to three months, depending on your usage, the size of your heating system, and your household conditions, such as whether or not you have pets or residents with allergies.
One of the best ways to prevent unusually dirty or clogged air filters from affecting the performance of your heating system is by having regular maintenance performed on your furnace. At The Lee Thompson Co., we offer two home comfort maintenance plans designed to protect against costly breakdowns.
Furnace Blower
The blower motor is essential for circulating warm air through the home. If your furnace won’t turn on, it could be due to a damaged or malfunctioning furnace blower. To determine if the furnace blower may be at fault, listen carefully to see if it’s running. If it seems unusually quiet, it might not be turning on.
Open the blower compartment and visually inspect the motor to ensure that it’s free of debris or other obstructions that could impede its operation. Next, check for a reset button, typically located near the motor housing. Press the button and wait several minutes to see if the motor restarts.
Finally, check for error codes. Error codes displayed on modern furnaces may indicate an issue with the blower motor. Refer to the furnace’s manual to determine what the problem could be and how to resolve it. If the motor looks extremely worn or burnt, it may need HVAC repair or parts replacement.
Air Vents
Blocked or closed air vents can disrupt airflow and prevent your furnace from heating effectively. Walk through your home and ensure that all vents and registers are fully open and unobstructed. Even a single closed air vent could create a pressure imbalance that negatively impacts the furnace’s performance.
Also, inspect the vents for dust, debris, or objects that could be obstructing airflow, such as a rug thrown over the vent or a piece of furniture blocking a register. Anything that covers or blocks air flow could prevent the furnace from working properly.
If airflow is still weak after removing any obstructions and cleaning the vents and registers, there may be a blockage in the ductwork. Minor blockages in the ductwork can sometimes be removed with a long brush or vacuum. However, large blockages may require an HVAC professional to perform duct cleaning or HVAC repair services.
Trust The Lee Thompson Co. for Expert Furnace Repair
A furnace that won’t turn on can be a hassle, especially during the colder months. However, there are many small issues that can be resolved with a little time and patience. From checking the thermostat to ensuring proper airflow, performing some basic troubleshooting can often restore your furnace’s functionality and keep your home warm and comfortable.
Serving Houston, TX, and the surrounding areas, The Lee Thompson Co. offers expert heating repair services to get your furnace up and running quickly to avoid disruptions to your comfort. Ask our team about our available discounts to save you money on your furnace repair or replacement, including $250 off any heat or AC replacement, $250 off any heat pump installation, $25 off any heat or AC repair, and free estimates on equipment replacements.