Air Conditioning Noises You Should Not Ignore

Strange noises coming from your air conditioner is not just an inconvenience. They could be a sign something is seriously wrong with your AC. While not all noises are a cause for concern, here are some noises your air conditioning system should never make.


If you hear a grinding noise coming from your unit, be sure to shut your AC off at the thermostat. Grinding is typically caused by a faulty condenser motor. The bearings inside the motor may be worn out and need to be repaired or replaced. Similarly, the fan blade may be broken and rubbing on other components. Either way, broken, faulty, and old parts are bad news for your AC, which is why you should turn your unit off and call a professional.



Hissing sounds indicate that there is probably a leak lurking somewhere, if you hear a hissing sound coming from your AC, it is likely either a ductwork issue or a refrigerant leak. A refrigerant leak can cause a hissing noise to come from your air conditioner. Refrigerant leaks can occur in either line or a coil and can cause inefficient cooling. This chemical is not only costly and necessary in order to cool your home, but a leak can be dangerous to humans, so if you suspect there’s a leak, call a professional technician right away.



Banging is usually a sure sign that there is a loose or broken part. This could be anything from a crankshaft to a connecting rod inside of the compressor. Or perhaps, your indoor blower is unbalanced. A banging noise may also indicate that your system needs a compressor replacement. In any case, if you hear this noise, we recommend turning off your air conditioning system and calling in a professional to avoid further damage.



A clanking noise is another sign that something has come loose or out-of-balance within your air conditioner. The parts inside the sealed unit have likely failed, and the compressor itself may have become loose, possibly necessitating a replacement. This sound can also mean that the indoor blower or outdoor fan and its blades are out of balance and hitting other parts. These types of issues will only get worse and create bigger problems, if ignored. Shut off the power to your system and schedule an appointment with a professional.



If there’s a constant clicking air conditioning noise, you could have a problem. The clicking of electrical components at start-up and shutdown is a normal part of the system’s operation, but constant or ongoing clicking is not typical. It could be a sign of a defective control or a failing thermostat.

If the unit is making a continuous clicking noise but will not turn on, it could be an electrical problem. If the clicking noise is coming from outside your home, it could be a problem with the compressor. Either way, you will want to get a technician out to your home as soon as possible to resolve the issue causing the clicking because it is almost always a bad sign.



A buzzing noise coming from your air conditioner is almost always indicative of an electrical issue with the condenser fan motor, relay switch, wiring, or another component of the system. Electrical issues can be dangerous and should not be taken lightly. If you hear a buzzing or sparking sound from your system, turn off your air conditioner and call a professional technician to assess the problem.

A buzzing noise from your outside unit could mean:

  • Loose parts
  • Debris in either the indoor or outdoor unit
  • Outdoor fan motor is loose or about to fail
  • Fan blades are loose or out of balance
  • The copper lines from outside to inside are rubbing against something
  • The condenser coil needs to be cleaned
  • The air filter needs to be changed
  • The blower is going bad or out of balance
  • Refrigerant leaks, resulting in your air conditioning freezing up. If it is conditioning not cooling, this could be why.



If you hear a high-pitched squealing noise coming from your air conditioner, it most likely means there is high internal pressure within your system’s compressor portion. Compressors typically have a sensor that signals the air conditioner to turn off if the pressure reaches a high level. However, the pressure can build up inside the air conditioner’s compressor and reach a dangerous level. If your AC is making this noise, we suggest turning off your system right away and calling a professional.



A humming sound generally is not serious, but it still signals that something inside your air conditioner is off. Loose parts and refrigerant piping can cause vibration and, if left unchecked, can lead to a more serious maintenance issue. For the most part, a light humming noise is completely normal. However, loud humming may be a sign that there are loose parts within your air conditioner. In certain cases, loose parts combined with refrigerant piping can cause excess vibration, leading to serious issues later on.



If your air conditioner is making a rattling noise, it may be a sign there is something wrong with the assembly motor or blower. The rattling noise may mean a small piece of the assembly motor or blower has come loose and is being tossed around the condenser unit outside.

This is a relatively easy fix and something you can do without a professional’s help. Turn off the power supply to your air conditioner and inspect the condenser unit to see if any components have become loose or disconnected. If the problem is not easy to find, then call a professional.



A high-pitched whistling noise is usually a bad sign. We recommend turning your air conditioner off right away and calling a professional. Whistling typically means there is a refrigerant leak somewhere in your system, which needs to be handled by a technician.



If your air conditioner is turning itself on and off every couple of minutes rather than the longer cycles you’re used to, this is called short-cycling. It can be caused by a few different things, such as electrical problems or compressor malfunctions. No matter what the cause is, however, the threat to your air conditioner is a concern.

Short-cycling cuts down on a system’s ability to cool your home, and accelerates the rate at which the AC wears down. Prolonged short-cycling will make your system more prone to breaking down, and will shorten its lifespan by a number of years. For this reason, it’s important that you call for repairs as soon as you notice your system short-cycling!


Call Us Today!

Don’t let a small problem turn into catastrophe. If your system needs repair or inspection before winter, call Aire-Tech on 951-926-1002. You can also visit our Contact page and complete the contact form.