5 Noises You Shouldn'T Hear From Your A/C System

Posted on: 15 October 2015


When it comes to keeping your home cool throughout the hottest periods of the year, your air conditioner is normally a silent partner. However, there are a lot of ways that your A/C system can make itself heard, especially when it needs service. When you hear these following noises, you'll know that it's time to have your A/C system looked at, either on your own or with the help of an experienced HVAC technician.

Rapid Whacking Noises

If you hear a constant whacking or thumping originating from the air handler while your A/C system is running, your blower fan blades may be coming into contact with something as the blades spin. Locate the blower fan assembly and make sure there aren't any obstructions causing contact with the blower fan blades. Make sure that all of the fan blades are straight, clean and free of any damage that could interfere with their operation.

Squealing Sounds

When you hear squealing sounds emanating from your A/C system, it usually means either one of two things:

  • The fan belt driving your A/C system's blower fan is loose or worn-out. The belt occasionally needs adjustments to remain relatively taut on its pulleys and, as it ages, it'll eventually need replacement.
  • If you don't have a belt-driven blower fan, then it's likely the blower motor itself needs lubrication. Without it, the heat generated from the constant friction can cause bearing failure, eventually leading to the motor's own failure.

Fortunately, the above are problems that you can handle on your own, if necessary:

  • Take a close look at the fan belt and check for signs of wear and tear. If the belt appears cracked, glazed, frayed or otherwise damaged or worn, replace it as soon as possible. Otherwise, carefully readjust the belt according to your A/C system's user or service manual guidelines.
  • Carefully lubricate the blower fan motor. According to Inspectapedia, most motors use SAE 20 oil, although others may have different lubrication requirements. If the blower fan uses a sealed motor, then you may need to have your HVAC technician inspect and replace the motor.

Constant Clicking

It's not unusual to hear a clicking sound as the A/C system cycles on and off. However, you shouldn't hear clicking sounds constantly or in rapid succession. Constant clicking noises can be an indication that the A/C system is short cycling, a problem that could severely reduce the life of your A/C system if left unchecked.

It's crucial to have your HVAC technician take a look at the potential causes of a short cycling problem, including low refrigerant levels, an improperly sized air conditioner and thermostat issues. These problems should be fixed as soon as possible by an air conditioning repair specialist if you want your A/C system to operate reliably and efficiently.

In other cases, clicking noises that occur as the A/C system runs could be caused by a bad relay switch. This is also something that your HVAC technician will need to take care of, since your technician has the tools and experience to troubleshoot this electrical issue.

Screaming Noises

If you suddenly hear screaming or very loud squealing from your A/C system, then you'll want to shut off your A/C system immediately. That sound you're hearing is the noise the compressor makes as dangerously high pressure builds up inside of the unit. Call your HVAC technician as soon as possible to have this problem fixed.

Hissing or Bubbling Noises

These noises usually indicate a refrigerant leak somewhere within the A/C system. In most cases, your HVAC technician can track down these leaks with the help of ultraviolet (UV) dye added in with the refrigerant. Regardless of how small the leak is, it should be repaired as soon as possible to preserve your A/C system's cooling performance and reliability.