No one expects their air conditioner to be completely quiet, but there are normal air conditioner noises and then there are the other kinds of noises that make you sit up and say, “What on earth was that?”
An unexpected air conditioner noise is often a sign of a problem. The question is whether it’s a minor problem, a major problem or just a sign that your air conditioner is getting older. Even if you know what a noise might mean, different problems can often cause the same type of noise, so it may take an air conditioning expert to figure out exactly what the problem is.
That being said, take a look at the following air conditioning noises that you definitely should take seriously.
1. Hissing or Whistling
A hissing sound that lasts for just a few seconds before stopping may not be a problem at all. It could be the sound of refrigerant gas in your expansion valve, for example. But a persistent hissing or whistling sound could be a sign of a refrigerant leak.
A refrigerant leak could occur in your refrigerant lines or in your internal valve. Leaky refrigerant lines could also make a bubbling sound. Leaky internal valves will worsen if left unchecked, and the hissing sound will intensify.
A leak should be investigated and fixed as soon as possible if you want to stay cool and prevent the leak from worsening. Keep the air conditioner off if you suspect a leak. Inhaling Freon — the refrigerant gas used in air conditioners — can be dangerous to your health.
Hissing could also be an indicator that the pressure inside of your air compressor is too high. In some cases, the hissing could intensify to a high-pitched shrieking sound. If you hear hissing, whistling or screaming coming from the compressor, turn the air conditioning unit off immediately. Leave it off until your air conditioning technician can look at it.
You may not notice a buzzing sound inside your house while your air conditioner is running, but you might notice it when you walk past the air conditioning unit that’s located outdoors.
Buzzing could indicate a problem with one of several air conditioner components: your condenser fan motor, your contactor relay switch or your circuit breakers, to name a few.
But one thing is certain: the buzzing sound means that you have an electrical problem. The buzz is what happens when electricity jumps between circuitry. In air conditioning units, this tends to happen as the unit gets older.
You can have an electrical problem even if the air conditioner seems to be working fine from the inside of your house. Ignoring it because your house is cooling normally could be dangerous, and it can definitely lead to greater damage requiring more expensive repairs later.
The National Fire Protection Association (NFPA) says that air conditioners accounted for an average of 2500 fires a year between 2006 and 2010. These fires are often the result of electrical problems.
If you’ve noticed buzzing coming from your outdoor unit, don’t take any risks. Shut the air conditioner off and call your air conditioning service.
3. Metallic Grinding Noise
A metal-on-metal grinding sound is rarely a good sign in any mechanical object. If your vehicle’s breaks made that sound, you’d take the car to a mechanic right away. Likewise, a metallic grinding sound could be serious business in an air conditioner as well.
Two of the most common causes for this kind of grinding noises are compressor problems and loose or damaged belts.
In compressors, the grinding noise is caused by the pistons that compress the refrigerant gas. They make this noise when the compressor is worn out, which means that you may need the compressor replaced entirely, and sometimes it means that it’s time to replace your entire air conditioning unit.
On the other hand, when a blower fan belt comes loose, it makes a grinding noise because the belt is rubbing against other components inside the air conditioner cabinet. While this will need to be fixed by an AC technician, the good news is that it’s a relatively minor repair.
However, if you keep running the air conditioner without having the belt repaired, it could result in much more extensive damage as the loose belt continues to come in contact with other air conditioner parts, potentially damaging them as well.
Either way, a grinding noise is not the kind of noise that can wait. Your best bet is to shut off the unit until you can have it inspected and repaired. That way, you won’t do any further damage to your air conditioning unit.
Your air conditioner is one of your most important home appliances, and using a good HVAC service is a vital part of keeping your air conditioner in top shape. Having unusual noises checked out by a professional protects your home’s air quality and your family’s safety as well as your own comfort. If you hear one of these noises, don’t wait to contact an air conditioning technician.