If your air conditioner is making strange noises that keep you awake at night, it is an indication that something is wrong. Some of these problems are more serious than others, but you should not ignore them. If you hear any of these noises, you should schedule an appointment with expert repair technicians to inspect your unit and troubleshoot the issue.
1. Hissing
Hearing hissing sounds from your unit means that air or gas attempts to escape. This can be a problem that originates from your ductwork, but it can also be a sign that your refrigerant is leaking. Aside from the hissing sound, you can also hear bubbling noises. Your refrigerant is an important component of your air conditioner.
It converts warm air to cool air. It consists of a tiny tube that you can see throughout your unit. The air from your unit should not interact with the air you breathe. A leaking refrigerant will not only prevent your unit from functioning properly but also harm your family and the environment. The leaks are classified as a toxic chemical that should only be handled by a certified HVAC technician.
2. Buzzing
A buzzing sound from your air conditioning unit indicates a mechanical or electrical issue. Mechanical issues range from malfunctioning condenser fan motor, compressor, small loose parts and damaged isolation feet. If you hear loud buzzing sounds, it might have to do with electrical problems with the relay switch, wiring or electrical current.
Once electrical issues are unattended, it will lead to a fire. It is important that you ensure safety in your home by turning off your air conditioner and scheduling an appointment with an HVAC technician. The contractor will examine your unit and diagnose the problem to find out if it is a mechanical or electrical issue.
3. Screaming
A screaming noise coming from your outside unit is an indicator that there is a problem with your compressor. More often than not, the sound resembles the sound that a screaming child produces. The noise is due to the internal pressure build-up. If you ignore the problem it can lead to the entire system malfunctioning. It can also cause the refrigerant to come out, which can threaten your home’s safety.

The first step you have to take in addressing the problem is by powering off your system. You will also need an HVAC professional to perform a thorough unit inspection. The technician will be the one to determine if your unit needs replacement or repair.
4. Screeching
A screeching sound means that the motor bearings or the belt in your compressor are the main sources of the problem. If you have modern air conditioning units, it has direct-drive motors, but older models operate on a belt-driven motor. If you hear your unit squeals, it might be due to a faulty belt. You can address the problem by calling an HVAC technician and replacing the belt.
For units that run on the direct-drive motor, the problem might come from the bearings inside your unit’s motor. If the problem is unaddressed, it will start making high-pitched squealing noises, which are signs that your unit is wearing out. The source of the sound usually comes from the outside unit. You can prevent further compressor damage by replacing the motor.
5. Banging or Rattling
Hearing banging or rattling noises from your unit means that there might be loose parts or debris inside it. It can be a fan blade, connecting rod or a twig. If you have a misaligned blower or a worn-out compressor, the problem might be due to the outdoor unit’s fan blades which are no longer balanced. The blades when not balanced can also clash with other components of your unit. Be sure to turn your air conditioner off before calling a professional to fix the problem.
Your unit will be carefully inspected to know the root cause of the problem. If it is a problem with the small loose parts, the technician will eliminate the obstacle and make sure that the loose-fitting components are tightened. For major parts like a blower or compressor, it should be replaced or repaired. An HVAC technician will inspect your unit for further damage caused by loose components and fix the unit accordingly.
The noises from your unit are great indicators that it is not running properly. Call an AC repair Dallas technician to schedule an appointment and get your cooling system back in order.