- Vibration of parts fitted to the system eg. tubes, rear panels, sheet metal parts etc.
- Wearing out of mounting bushes
- Compressor noise in an air sound
- Outdoor/indoor fan (aircon) or air-cutting noise
If all these conditions have been checked and the air conditioner is OK, then it has gone into defrost mode.
When it is difficult to ascertain the source of the noise, use the noise tester i.e. dB metre.
Hence, the compressor may not be the main source of noise.
If the sound is heard only in IDUs or evaporators, the noise could be due to the running of the fan/blower motor or due to an object touching the fan blade.