Loose or Unsecured Parts: Over time, components within your air conditioner can become loose due to regular wear and tear. When these parts move around, they can create banging noises as the unit turns off and on. Duct Expansion and Contraction: Your ductwork can expand and contract with temperature changes.
In many cases this will require a compressor replacement; in others, the loose part simply needs to be tightened or replaced. An unbalanced blower. The blower is the “fan” unit, and it's usually located indoors. If it's unbalanced it will create a banging or knocking noise as the fan spins.
The sound you're hearing is the probably compressor. It is not unusual for them to make a ``clunk'' type noise on start up, shut down or both. The compressor is spring mounted and sits inside a metal shell. Over time the springs loose some of their spring tension and contributes to the sound.
If things get caught in your system's fan, it can cause thumping. If you hear any loud thumping or banging, make sure to check your system for any trapped debris before calling an HVAC professional. This sound can also be a sign of a part on the indoor blower or outdoor fan that's loose or out-of-balance.
If you're hearing unusual vibrating, rattling or clunking noises when the system turns on, or while it runs a cycle, it could be the fault of the compressor. Compressors usually go bad in older air conditioners and are quite expensive to replace, so your best bet might be to buy a new air conditioner.
Banging Sounds Coming From the HVAC Ductwork
This type of noise usually occurs in quick, short bursts. It is the result of expansion and contraction in the duct walls as internal temperatures rise or fall. This type of noise can also be the result of pressure changes within the ducting.
Clanging, Rattling, and Banging
Clanging and rattling noises are a sign that a loose part is hitting another part. For example, the compressor or blower unit. These loose parts will eventually disconnect, which will create an even more loud banging noise. It can sound like someone is shaking keys inside your AC!
If the knocking noise is coming from your AC compressor (the outdoor unit), the fan or one of its blades might be loose. This can cause the fan's blades to bang into other parts of the compressor, creating a loud knocking noise.
These noises could indicate an issue with the blower, a loose part, or even a failing compressor. Continuing to run your AC in this state can cause more damage. It is best to turn it off and call a professional HVAC technician to diagnose and fix the issue.
In most cases, the flapping is caused by a piece of debris lodged in between one or more blades of the fan blower inside the unit. Large pieces of mulch, pine straw, clumps of grass clippings, trash or even a dead lizard, frog or bird can all become stuck inside the unit.
On average, AC compressor costs range from $800 to $2,300, with most folks paying $1,200 for a new one. However, your price will vary depending on factors like the size and brand of your compressor. Before you schedule your replacement, read on to learn about all AC compressor cost factors.
POPPING/CRACKLING
If your AC unit is making a popping noise, it could be as a result of ice forming, either because the temperature is set too low or because of water drainage issues. If water can reach some of the more sensitive areas of your system, it could cause lasting (and expensive) damage.
If your furnace is making a clicking noise, this is a sign of an issue occurring during the heating cycle. When you hear clicking from your furnace, you should contact an HVAC professional immediately, as this strange sound may indicate a faulty igniter or gas valve. Issues with these parts can result in a gas leak.
Worn-out parts are a common cause of air conditioner clunking noises. Fan motor and blades, motor mounts, blower motor, compressors, and belts can all wear down over time and produce unusual sounds as they malfunction. Blower motors pull in warm air to be cooled, and then push cool air throughout your home.
If, on inspection, you hear chattering, whining, squealing, chirping, or rattling sounds coming from the AC compressor, it is time for AC service. Sometimes the commotion only erupts when you engage the AC switch. Some noises remain constant. Compressor noises result from either a faulty clutch or a seizing shaft.
Inside your air ducts, two processes occur—contraction and expansion. As temperatures rise, your air ducts' metal parts heat up. These parts will then move around, producing a knocking sound in furnace vents. Fortunately, this is entirely normal and generally doesn't signal an issue.
It's recommended that you service your home air conditioning system at least once every year. The same goes for your heating system.
If the filter is dirty or was not installed correctly, air may not move through it efficiently, which will cause a backup. Once the furnace cycles off, the homeowner will hear a loud banging noise as the metal in the furnace expands due to the excess air.
An imbalanced or failing indoor blower motor or outdoor fan motor, or worn-out bearings also cause a loud banging or knocking sound. Improper installation, undersized ductwork, and failing compressor may also produce unusual system sounds.
Low AC refrigerant can put a strain on the AC compressor, causing it to work under duress. This stress can result in strange noises like grinding or hissing sounds coming from the unit. A hissing or bubbling noise indicates a leak, hissing is escaping as a gas, while bubbling indicates it is escaping as a liquid.
The compressor is one of the most important parts of your AC unit and is also one of the most common causes of loud buzzing sounds. If the compressor is not working properly, it can make a lot of noise as it tries to start up or cool down the unit.
A sure sign of a bad AC capacitor is a humming sound from within the access panel.
Generally speaking, to have a shop properly change an AC compressor and related components, flush, and re-fill the AC system will run between $750 – 1500.00. Depending on the model and cost of the parts in general, this cost could be even higher.
Banging Noise
The indoor blower fan may have loose fan blades rattling around as the motor rotates the fan. Banging from the compressor is a sign of loose parts inside the compressor, such as a piston pin or connector rod, as well as parts on the outside of the compressor.