external air conditioner unit

The external air conditioner unit is buzzing: what is the reason and what to do?

The external unit of the air conditioner often becomes a source of additional noise. Most of them are absolutely normal, including a slight hum. But if recently your air conditioner has started to make extraneous sounds and buzz louder than usual, you should pay attention to this.

In this article, we will tell you in detail why the air conditioner is buzzing, what are the causes of excessive noise coming from the outdoor unit, and what can be done about it.

General information

what to do if the outdoor unit is buzzing

Any air conditioner emits a hum by default. When the windows are open, it can be clearly heard, especially at night. But you should understand that the level of this noise should not be prohibitive. If the hum from the outdoor unit is heard even with the window closed, the device probably needs diagnostics.

Also keep in mind that budget air conditioners often work louder, because they are made of lower-quality components, and the assembly leaves much to be desired. In the article below, we talk in detail about the best air conditioners that are worth considering for purchase.

Causes of loud buzzing

Contamination of the outdoor unit

Insects, dirt and pollen get into the body of the outdoor unit, polluting it in just one summer season, and become the most common cause of extraneous hum during the operation of the split system. This is not surprising, because the outdoor unit needs the same regular cleaning as the internal one.

And if there are no problems with the internal one, then cleaning the outdoor unit is often fraught with difficulties and even a danger to health. If the unit is installed in an apartment building and not on the first floor, it is worth calling a specialist from the service center.

Well, if you can get to the outdoor unit without danger, you can save a little and clean it yourself. We have already described how to do this in the article below.

Problems with the fan

A fan is located inside the outdoor unit. Its blades are made of plastic, which, unfortunately, cannot boast of an infinite service life. The blades crack, their edges break off, which causes a crackling or rumbling sound at high speeds. In this case, you need to replace the fan, but this task should be entrusted to an experienced specialist.

Also, the problem may be hidden in the fan bearing. If everything is in order with the blades, it is necessary to replace the bearing by first removing the plastic part of the fan. The bearing is selected in a strictly identical size.

Temperature problems

air conditioner icing

Humming may occur due to ice formed on the outdoor unit when working in heating mode. Often, ice is formed when the radiator is dirty, problems on the highway or a lack of freon. If you have direct access to the outdoor unit (for example, you live on the first floor), turn off the device and wait for complete thawing. Then clean the block from dirt.

If cleaning did not help to get rid of the problem and you can not do without an air conditioner, reduce the heating temperature by a few degrees and wait for the master from the service center.

Also, buzzing can occur when there is a large difference between the temperature in the room and outside. In this case, we also recommend lowering the temperature, or putting a so-called winter kit. Its installation is carried out by the service service, which provides maintenance of air conditioning systems. You can also save a little and simply insulate the outdoor unit instead of the winter kit, but this is not the most effective method.

Missing / worn rubber gaskets

rubber gaskets at the air conditioner

To mount the outdoor unit on the wall, brackets are used. The device is screwed onto the brackets with bolts. There must be a rubber gasket between the bracket and the bolt, it dampens vibration. The gasket may wear out over time, or the masters may forget about it even at the installation stage. Soon, the vibration will begin to be transmitted directly to the metal brackets, which is why you will hear a characteristic buzz.

The average service life of cheap gaskets is no more than 1 year. In order not to change them every year, put high-quality ones. We recommend that you entrust this task to the master from the service center. Especially if it is installed at a height of more than 2 meters.

Also pay attention, it is possible that the hum is emitted by the parts of the block that are located too close to each other. In this case, you need to put a thermal insulation material or rubber gaskets to get rid of the hum.

Poor-quality assembly of the block

Devices of the economy segment are often assembled at cheap factories from low-quality materials, which is why they can emit a hum by themselves. It does not matter which operating mode is selected. The buzzing may appear spontaneously or be a constant intruder of your peace. In any case, if everything is fine with the system, then the hum comes from the unit due to its poor-quality assembly at the factory.

However, this problem can be partially fixed. First, you need to tighten all the bolts properly. They could have dispersed due to vibration during operation. Secondly, you can put rubber gaskets between the housing and the compressor to extinguish excessive vibration. Such gaskets can be made independently by cutting them out of ordinary rubber. The recommended thickness of the gasket should be at least 5 mm.

Other components of the system, such as copper tubes, can also emit extraneous sounds. If the manufacturer decided to save money and did not heat-insulate them, do it yourself or trust the master. Thermal insulation can be bought in free access. It also recommends isolating any components that may become a source of vibration.

Other reasons

There is an engine inside the compressor that needs regular oil change. If it is of poor quality or even ends, the compressor will vibrate excessively, thereby emitting a hum. Only a specialist can replace the oil.

He will also perform additional diagnostics to determine whether the compressor is working properly, and will replace the rubber gaskets between the compressor and the fasteners. These works cannot be performed independently.

If the air conditioner is turned off, it makes extraneous sounds, most likely they come from the indoor unit.


The external unit of the air conditioner, as well as the internal unit of the air conditioner, can make noise during operation or even when switched off. Budget devices make louder noise, because less high-quality components are used during their assembly. It is also worth paying attention to the words of the manufacturer. After all, split systems designed to work in the bedroom or office traditionally work quieter.

But if over time the split system began to make suspiciously loud sounds, pay attention to them. Try to find out what the reason is. If you are unable to overcome the problem on your own, contact the service center for help. We wish you good luck!

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