Why is My Air Conditioner Buzzing When It is Off?

Updated: October 10, 2022

The soft hum of an air conditioner on a hot summer day is relaxing enough to lull you right into a nap. However, sometimes you hear a different sound that’s not so comforting. When the hum evolves into a loud, disturbing buzz, it’s worth looking into the cause. Besides the annoyance, that noise can be indicative of a severe internal problem that could interfere with the efficient and safe operation of the unit. Here are some of the possible reasons your air conditioner may be buzzing, even when it’s not operating.


Why is My Air Conditioner Buzzing When It is Off?

If you notice your air conditioner is buzzing when it is not operating, any of the following reasons may be the problem:

  • One possibility is that the contactor relay switch may not be working correctly. This component controls how the electricity gets to the compressor. If it’s malfunctioning, power and amperage may be impacted, and you may hear the buzzing sound. The easiest fix is usually to replace the contactor relay switch
  • The electrical connections may be loose. Over time, this can happen as the unit vibrates during operation, resulting in short circuits and an increased risk of fire. A problem of this nature is an emergency for your health and safety.
  • The condenser fan blows from the outside of the unit when it comes on. A damaged condenser fan motor may cause an operational failure, or the compressor may malfunction, leaving the unit unable to pressurize and cool the refrigerant. A compressor failure may also interfere with the voltage flowing through the unit at the right amperage. If the internal blower works but the fan doesn’t turn, the motor buzzes. Sometimes this happens when debris interferes with the fan or the fan itself fails.
  • Your air conditioner has many components, and most of them are capable of failing. The internal parts may come loose and damage other elements in the vicinity. Loose parts can also cause uneven wear and tear on the unit and can keep the fan from turning as well.
  • The compressor sits at the base of the unit on rubber isolation feet. The seating may have worn down over time or because of exposure, leaving the unit unbalanced.
  • Restricted airflow or a refrigerant leak can cause the unit to freeze up. You may see ice on the buzzing air conditioning unit itself if this happens. You may also notice a drop in the efficiency of your AC unit. The first step to remedy this problem is to turn off the unit and let it thaw out. If the unit still doesn’t function properly when you restart it, call in professional help.

What Should I Do About the Buzzing?

If you hear a buzzing from your air conditioner when it’s not running, you should turn it off right away and call a professional for help. Because it may be a sign of an electrical problem, it’s too dangerous to try to fix it yourself. The professionals at Herrmann Services know where and how to check for the cause of buzzing safely. Our trained technicians will inspect the filters, the AC Freon, and all the points requiring lubrication, to name a few. They’ll also check all the parts for wear and tear, remove accumulated foreign materials, and inspect the coil for proper airflow. Dirt or some other foreign substance may cause a problem inside the unit.

Once we’ve made the proper repairs, we can give you some tips on keeping your AC unit running smoothly. You may want to consider a routine maintenance plan to avoid these issues in the future. Herrmann Services can share all of your options with you so you can choose the one that fits your needs. Call us today: (513) 434-3168.

Photo Credit to Alpa Prod

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