During normal air conditioning operations, it is perfectly natural to heat a light humming noise in the background or the occasional rush of air at the vent. But, if you hear odd noises, this is a sure sign that something is wrong and the type of noise can give you some helpful cues on the possible causes. In this article, we will look at six common AC problem noises to help you make informed decisions on repairs and replacements.
1. Clicking
When an AC system is started or shut down, you may hear a rapid clicking noise for a short time. But, if you can hear a clicking sound when the air conditioner is running, there is a problem to solve. The most likely causes are a thermostat that needs replacement or there may be an electrical issue. If you hear clicking noises during normal operations, contact an HVAC technician to check the system.
2. Hissing
The AC system cools a space indirectly by removing the heat and dispersing it outdoors. This may seem like a trivial distinction, but it’s important to understand that this is a cycling process that’s repeated until the system is shut down. The system relies on a refrigerant that changes from a superheated gas to a liquid and back again. This process changes the refrigerant from low-pressure to high-pressure over and over again to collect the heat and move it outside.
The source of a hissing sound when the system is running is probably a refrigerant leak that should be investigated by an HVAC technician. Although it’s tempting to attempt to top up the refrigerant yourself, this should be avoided. There are many different types of refrigerant and adding the product could compromise the performance and efficiency. Also, simply adding more refrigerant will not fix the refrigerant leak and the same problem will occur again. Another possible cause of hissing is an early sign of a build up of high pressure in the compressor unit. This is an expensive component that should be fixed as a priority to prevent an unexpected and expensive repair later.
3. Buzzing
The source of this noise is usually heard at the outdoor AC unit. The usual cause is a faulty compressor unit or a failing condenser fan. Another common problem is degraded rubber feet at the base of the condenser which can lead to annoying vibrating noises. If a buzzing noise is emanating from the indoor unit, this can indicate that the evaporator coils are frozen. Contact a local HVAC specialist to determine the exact cause of the problem and to fix it for you to prevent a more expensive repair or replacement later.
4. Banging
A banging noise is usually a sign that something is really wrong in any system that has moving mechanical components. When a part becomes loose or it has broken away from its housing, it is likely to fail and it may even damage other components too. Most banging noises are caused by a compressor that has a loose piston pin or connector rod. If the banging noise is more like a rattling sound, it’s likely that the indoor blower fan is loose and moving around. Ignoring these sounds is inadvisable because they can significantly increase the future repair costs when the components fail entirely.
5. Squealing
Again, a brief squealing noise when the air conditioner first starts is pretty normal. This sound may last for 10-15 seconds before the system settles down. If you can still hear squealing after this brief period, this is a sure sign that something is wrong. There are two possible causes, the fan belt may be loose or there could be a build up of internal pressure in the system. Replacing a worn fan belt is a pretty simple task for an HVAC technician and a build up of pressure may take a little longer to fix.
6. Popping
This sound can be a little confusing because it is related to the HVAC system, but it may seem like it’s coming from multiple locations when the system is running. This is understandable because a popping noise is usually a sign that the ductwork is in poor shape.
This may be more noticeable when the system is started or stopped. A rush of air into the ductwork can disrupt loose or badly fitted joints and cause an annoying popping noise. Aside from the disruption, ductwork that’s in bad shape will lower the energy efficiency of the entire system because treated air can escape. It’s a good idea to get the ductwork checked during regularly scheduled maintenance because a lot of efficiency can be lost there. If the ductwork is in poor shape, it’s usually cheaper to replace it entirely.
How to Reduce AC System Noises
It’s a bad idea to ignore any of the aforementioned six AC system noises. But, if the regular running noises of the system are a problem there are three techniques that can be used to lower the noise profile. They are:
1. Add a Sound Blanket
The noisiest component in the entire AC system is the compressor and if the outdoor unit is located near a bedroom it can be annoying. A simple solution is to remove the outdoor unit cover and cover the compressor with a sound blanket. The sound will be muffled and there will be no loss of performance or energy efficiency.
2. Add Plants
The outdoor AC unit can be noisy, but during the day this tends to be less obvious. At night there are fewer distractions and the sounds that the system makes may become a problem. Adding some plants around the equipment and some larger houseplants near the windows can help to deaden the sound.
As an added bonus, the indoor plants will increase the oxygen levels in the home which will improve the indoor air quality (IAQ). This is a great solution, but the outdoor plants need to be pruned back periodically to prevent them from interfering with normal operations.
3. Add Sound Absorbing Fences
To muffle the sound of the outdoor unit you can add sound absorbing fences. These usually have overlapping boards made from sound deadening materials that can significantly lower the ambient noises. The fences should be installed at least three feet away from the unit to ensure that they don’t interfere with the airflow required to run the system.
If you can hear strange AC system noises, contact your local heating and specialist.