AUX air conditioner service manual
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Chapter 9 Maintenance Cases of Noise and water leakage of AC
Section one cases of air conditioner noise reduction
Air conditioner noise is a common problem seen in our maintenance work, causes of which shall be
paid attention to. Noise can be classified based on Positions: indoor noise, outdoor noise; based on
sound types: friction noise, wind sound, air flow sound, and electromagnetic sound; based on causes:
assembly problems, structure design problems, components and parts quality problems and
installation problems. We shall distinguish sound types, positions and causes of air conditioner noise,
and deal with the problems accordingly.
⒈ Common noises of indoor unit
⑴Dirt in indoor unit
⑵Indoor fan motor axis, poor concentricity and fix screw becoming loose
⑶Poor concentricity of indoor fan, blade breakage and wearing of left blade axis bush
⑷Loosing of the panel and the auto-switch
⑸Abnormal sound (friction sound from connection parts) from step motor and horizontal air blade,
⑹Whistle (poor balance of blades, if necessary change a blade; or 25A failure of evaporator itself)
⑺Refrigerant flow sound of indoor unit (line bending position 32M and capillary 100S)
⑻Air inlet was obstructed because of dirt filter
2. Common noises of outdoor unit
⑴Loud noise from compressor
⑵Tube vibrating and touching outdoor casing
⑶Whistle from blades (blade breakage)
⑷ Loud sound from outdoor fan motor( replace 70W ， 930rmp,YDK48-6-354 3UF with
YDK48-6A-354 4UF)
⑸Outdoor blade touching outdoor casing, condenser or steel grille
⑹Sympathetic vibration of outdoor unit, especially removing the motor bracket of the small outdoor
unit
⑺Outdoor steel grille colliding with outdoor casing
⑻Indoor unit motor frame becoming loose
⑼Air conditioner installation holder becoming loose
⑽Improper installation position of outdoor unit
⒊ Method to find noise positions
⑴Denying one by one: When it is difficult to find noise sources, for example, to decide it’s
compressor or outdoor motor producing noises, firstly we should break off compressor, and listen if
outdoor motor produces noise, if not, it’s compressor creating noises.
Case 1: Blade axis of indoor unit colliding with rubber seat
Unit Model：ASW-H12B4/HY
Phenomena： Loud indoor noises
Cause Analysis: indoor unit creates same sound in both cooling and ventilation modes, with similar
fault phenomena. Noise was louder when air conditioner was turned on. Removed panel and shell of
indoor unit, fault still remained the same and sound came from left bearing, so maintenance personnel
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