Bangs, booms, pops, and other unfamiliar sounds from your HVAC system could indicate that something is amiss. While most furnaces and air conditioners make some noise, new or unusually loud noises often mean that a component is malfunctioning or your unit is not running as effectively as it once did. Different types of noises can point to different problems. Listen carefully to distinguish what type of sound you’re hearing.
1. Squealing
High-pitched squealing is often caused by something minor, such as a bad belt. If you hear a squealing noise coming from your blower motor, check the belt before it has the chance to break. If it does break, your blower will stop turning. A noisy motor can also be remedied by adding lubricant. Many blower motors contain oil ports where you can add the oil yourself. Check with the manufacturer to ensure you’re using the proper oil.
2. Banging
Banging from your air conditioner is typically a sign that a component inside the unit is broken or loose. Look inside the AC compressor to locate detached components, such as a piston pin, connecting rod, or crankshaft. A banging noise from your HVAC system could also signify the need for a compressor replacement.
3. Rumbling
If your furnace is making a strange rumbling sound, you could be looking at a corroded or dirty heat exchanger. Like all HVAC system equipment, heat exchangers can collect dirt, dust, and grime. The rumbling sound from a heat exchanger may be accompanied by a reduction in the equipment’s production as the system is forced to work harder. A thorough cleaning by a professional may be enough to remedy this problem.
4. Clicking
At the start and end of a cooling or heating cycle, it’s normal to hear a distinct clicking noise. However, clicking that is ongoing or occurs in the midst of a cycle is not typical. Clicking is often associated with a failing thermostat, defective control, or failure in one of the electrical components. As there are many electrical parts in the average HVAC unit, hire a professional to inspect your system.
5. Rattling
Rattling noises from your HVAC system are often not related to the cooling or heating units themselves, but rather the ductwork. As ducts age, the seals can begin to fail and the connections loosen. Static pressure can cause the loose metal ducts to knock against each other, creating a rattling noise.
6. Thwapping
“Thwapping” is an unusual sound that may be made when the blower is running. The sound is similar to the noise made by a playing card placed in the spokes of a bicycle tire. If you hear such a noise, there may be something stuck in the blower blades. As the blades turn, the loose component may come in contact with the blades, causing the odd noise. Promptly remove the loose part to prevent your motor from wearing out.
7. Buzzing
A strange buzzing sound from your outside HVAC unit can be alarming. As this type of noise can have numerous causes, it’s essential to check for each potential cause to narrow down the possible culprits. Buzzing sounds can be caused by loose parts, out of balance fan blades, debris in the unit, a dirty condenser coil or filter, a blower that’s going bad, or a refrigerant leak that’s causing your air conditioner to freeze up.
8. Grinding
Grinding or scraping noises coming from your furnace are often more serious than your typical repair. These sounds may indicate a failing blower motor. Your blower motor can fail for a number of reasons, with the most common being old age. Neglecting to perform proper maintenance on your HVAC system can also lead to premature aging.
9. Humming
Most HVAC systems will make a quiet humming sound while in use. However, if the humming becomes louder or is accompanied by banging, grinding, or other sounds, it could indicate a more serious problem. Loose parts inside the unit can cause vibration. If left unchecked, this vibration can cause more costly maintenance issues. If the compressor hums when turned on but refuses to start, the problem is likely the motor.
10. Huffing
A furnace that huffs and puffs is often related to a corroded or faulty gas valve or burner. Burners can develop problems for a variety of reasons, such as valve issues, rust flakes, dirt, or a loss of connection of the gas line. If the burner shuts off entirely, you will not receive any heat to your home. Problems with the gas valve or burner can also result in diminished heat over time.
11. Booming
If a booming sound seems to be coming from your ductwork, look at the connection of the duct trunk and plenum. As this connection receives the most dramatic swing in temperature, problems can arise resulting in strange noises. Inadequate dampers or expansion joints may not properly isolate the sound. The result is an audible boom that echoes throughout the ductwork.
12. Scratching
Scratching noises in your HVAC system are often unrelated to the health of your units. If you peek inside the unit, you may find small critters scratching the various components. Rats, mice, squirrels, large insects, and even raccoons can find their way into your HVAC system, creating chaos in their wake. Removing the intruder is essential to avoid costly damage.
If you’re tired of dealing with a noisy HVAC system, you may be wondering which units will give you peace and quiet. Today there are a number of units on the market that offer near-silent performance. To determine the loudness of an HVAC system, look at its decibel rating (dB). The lower the decibel rating, the quieter your system will be. In addition to using equipment silencers, choose a modern HVAC system with variable fan speeds, noise-reducing fan blades, compressor insulation mounts, and an insulated base pan. If you’re experiencing strange noises from your HVAC system, contact the professionals at R. Brooks to diagnose and remedy the problem.
