The part(s) or condition(s) listed below for the symptom Furnace is noisy or loud are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.
Furnace Blower Not Running? Gas Furnace Troubleshooting
Furnace Blower Runs All The Time? Gas Furnace Troubleshooting
Furnace Noisy Or Loud? Gas Furnace Troubleshooting
Furnace Starts Then Stops? Gas Furnace Troubleshooting
Furnace Not Heating? Gas Furnace Troubleshooting
Replace Furnace Filters - Tech Tips from Repair ClinicA clogged air filter can cause strange whistling or low humming noises. The air filter is a critical part of heating and cooling your home. Not only does it filter the circulated air you breathe, it also helps keep the furnace heat exchanger, air ducts, and air conditioner coil from clogging up. It is recommended to replace the air filter at least every 6 months or sooner depending on the conditions.
The blower wheel blows air out of the furnace and through the house. The blower wheel is attached to the blower motor shaft with a set screw. If the set screw is loose, the blower wheel will wobble on the motor shaft, and the wheel will be noisy as it turns. Check the set screw to ensure that it is properly tightened. Next, inspect the wheel for damage. If the blower wheel is damaged, replace it.
Over time, the bearings in the blower motor wear out, causing the motor to become noisy. Some furnace motors can be lubricated—if your furnace motor can be lubricated, try lubricating it first. If lubricating the motor doesn’t solve the problem, or if your motor can’t be lubricated, replace the motor.
The draft inducer motor draws air into the burner and then exhausts it out the flue. If the motor bearings are worn out, the motor will be loud. If the draft inducer motor is unusually noisy, replace it.
The flame sensor monitors the burner to detect whether or not a flame is present. A defective sensor might fail to detect a flame, causing the control board to shut off voltage to the gas valve to prevent the release of gas. Sometimes, if the flame sensor is dirty and only intermittently sensing the flame is present, the control board will shut off the gas and try to relight the burner several times which can result in a lot of unusual noises. Try cleaning the flame sensor with a fine abrasive pad. If the furnace still doesn’t light properly, replace the flame sensor.
The draft inducer blower wheel blows air through the burner system. Inspect the blower wheel for damage (such as a separated center hub or broken fins). If the blower wheel is damaged, replace it.
Over time, the blower wheel can become clogged with dust and debris which can result in noisy operation. You can try cleaning the blower wheel with compressed air or with a soft bristle brush. Use caution when trying to clean the blower wheel as the fins are sharp and can be easily damaged. If the blower wheel and housing is damaged, the assembly will need to be replaced.
The blower motor or draft inducer fan motor fan blade may be loose on the motor shaft and striking the housing, or debris may be caught in the fan blade. This can cause the furnace to be noisy during operation. Inspect the fan blade to ensure to ensure it is clean, unobstructed, and is fully seated on the motor shaft and secured tightly. If the fan blade appears damaged, you should replace if applicable.
Some furnaces have burner tubes with ports or slots to distribute the heat evenly in the heat exchanger. If the burner ports or slots get clogged the burner may not light properly and cause a whooshing noise when the burner lights or a whirring noise after it lights. Most burner tubes can be removed and cleaned. If the burner is damaged it will need to be replaced.
The gas valve opens to allow gas to flow into the burner. If the gas valve is defective, it may not let the proper amount of gas into the burner causing delayed ignition. If the burners and burner orifices are clean but the burners are still noisy (and will not light correctly), then the gas valve may need to be replaced.
Over time the blower wheel can become clogged with dust and debris or the set screw securing the blower wheel to the motor shaft can loosen. This can cause the blower to become unbalanced and vibrate or rub against the housing. You can try tightening or replacing the set screw to fix the problem. You can also try cleaning the blower wheel with compressed air or with a soft bristle brush. Use caution when trying to clean the blower wheel as the fins are sharp and can be easily damaged. If the blower wheel and housing is damaged, the assembly will need to be replaced.
Over time, the bearings in the blower motor or the draft inducer fan motor can wear out, causing the motor to become noisy. Some furnace motors can be lubricated—if your furnace motor can be lubricated, try lubricating it first. If lubricating the motor doesn’t solve the problem, or if your motor can’t be lubricated, replace the motor.
Over time, the bearings in the blower motor or the draft inducer fan motor can wear out, causing the motor to become noisy. Some furnace motors can be lubricated—if your furnace motor can be lubricated, try lubricating it first. If lubricating the motor doesn’t solve the problem, or if your motor can’t be lubricated, replace the motor.
Over time the blower wheel can become clogged with dust and debris or the set screw securing the blower wheel to the motor shaft can loosen. This can cause the blower to become unbalanced and vibrate or rub against the housing. You can try tightening or replacing the set screw to fix the problem. You can also try cleaning the blower wheel with compressed air or with a soft bristle brush. Use caution when trying to clean the blower wheel as the fins are sharp and can be easily damaged. If the blower wheel and housing is damaged, the assembly will need to be replaced.
The draft inducer motor assembly draws air into the burner and then exhausts it out the flue. If the motor bearings are worn out, the motor will be loud. If the draft inducer motor assembly is unusually noisy, replace it.
