Why does my air conditioner make a cracking sound or sound like water flowing?

A cracking sound is generated by the expansion and contraction of the front panel due to changes in temperature, and is normal. A sound like water flowing is the sound of refrigerant flowing inside the air conditioner unit, while a sound like compressed air releasing is the sound of dehumidifying water being processed inside the unit. These sounds do not indicate a malfunction. (Page 24)