After the power switch is turned on, the air outlet flaps operate. When the unit is turned on, the microcomputer operates the flaps to determine their position for initialization. The air conditioner produces a water flowing sound. The water flowing sound is produced by the refrigerant that flows inside the air conditioner. The air conditioner produces an air releasing sound. The air releasing sound is caused by a change of the refrigerant flow direction. The air conditioner stops operation (Operation lamp remains lit). When power supply voltage fluctuates largely, the air conditioner may stop operating to protect the equipment. The air conditioning produces a crackling sound. Plastic parts such as the front panel produces a crackling sound when they expand or contract slightly due to temperature change. The air flow suddenly becomes stronger during a heating operation. When the air flow is set to LOW, the amount of air flow increases when the overload control is activated.

The air outlet flaps do not operate at the same time in the master and slave indoor units of a simultaneous operation multi-unit. There is a slight time lag in the signal transmission between the master and slave units. It does not denote a malfunction. The air outlet flaps sometimes operate during a cooling operation. The air outlet flaps move when the frost prevention or ceiling soiling prevention function is activated. The drain pump continues operating after a cooling operation stops. After the air conditioner stops operating, the drain pump operates for several minutes in order to discharge condensate from the drain pan (condensate receiving tray). The indoor unit fan operates after a heating operation stops (in an air conditioner equipped with a heater). In order to reduce the temperature of the heater, the fan operates 60 to 100 seconds after the air conditioner stops operating. The outdoor unit discharges water or steam. The defrost operation activated in the heating mode removes frost, which turns into water or steam.

When the air outlet swing function is set to ON, the flaps remain at a horizontal position. The flaps remain at the same position when room temperature reaches the set level and the thermostat turns off. When the thermostat is off, the flaps do not swing. In the microcomputer-controlled dry mode, the indoor unit fan operates at L for one minute when the outdoor unit (compressor) is not operating. The monitoring function forcibly operates the indoor unit fan for one minute. The air conditioner does not blow air immediately after it starts operation in the heating mode. The air conditioner conducts a "warm-up" operation first so that it won't blow cold air in the heating mode. The air conditioner does not start operation immediately after it is turned on. To reduce excessive load in a restart, the air conditioner does not operate for three minutes when the ON switch is pressed immediately after it is shut down or when the operation mode (setting) is changed using the remote controller.