Control/conditions

Unit operation

 

Explanation

 

 

 

 

HEAT

The thermostat turns ON.

The indoor unit is stopped.

The unit operated before, and the temperature of

 

 

 

the indoor heat exchanger is relatively warm.

 

 

 

Therefore,the fan speed may start at the set fan

 

 

 

speed at the same time that the thermostat turns

 

 

 

ON.

 

 

 

 

 

 

 

When defrost operation

Non-stop defrost

Defrost operation begins based on outdoor

 

begins, frost has formed

 

heat exchanger temperature and outdoor

 

on the outdoor unit

 

air temperature conditions.

 

(when the ambient air

Indoor fan : Stopped

 

 

 

 

temperature is low).

Outdoor fan : Stopped

Non-stop defrost (Refer to Fig. 1)

 

 

Compressor : 80 Hz

1. After HEAT operation begins, the temperature

 

 

of the outdoor heat exchanger is at or below the

 

 

Solenoid valve (for hot gas bypass): ON

 

 

L1 line for 35 minutes.

 

 

4-way valve : Remains ON

 

 

(If outdoor air temperature is less than 26.6 °F,

 

 

Operation lamp : Red and orange ON

the time is 48 minutes)

 

 

alternately

2. After HEAT operation begins, the temperature

 

 

 

of the outdoor heat exchanger is at or below the

 

 

 

L2 line for 120 minutes.

 

 

 

 

 

 

 

 

 

The 4-way valve remains ON during defrost.

 

 

 

 

 

 

 

 

 

The outdoor fan stops and the solenoid

 

 

 

valve turns ON, allowing the refrigerant to

 

 

 

bypass the indoor unit.

 

 

 

 

 

 

 

 

 

The operating frequency during defrost is

 

 

 

80 Hz. (Frequency is lowered if the current

 

 

 

peak cut-off function is activated.)

 

 

 

 

 

 

 

 

 

The maximum length of a single defrost

 

 

 

operation is 12 minutes.

 

 

 

For the outdoor heat exchanger temperature

 

 

 

conditions for ending defrost, refer to Table 1.

 

 

 

 

 

 

 

Defrost release

Indoor fan turns ON.

 

 

 

 

 

After 10 seconds, the solenoid valve

 

 

 

 

 

(for hot gas bypass) turns OFF.

 

 

 

 

 

When the cold air feel has disappeared,

 

 

 

 

 

 

 

 

 

 

the indoor fan starts and gradually increases

 

 

 

 

 

speed until it reaches the set speed.

 

 

 

 

 

 

 

 

 

 

STOP

All indicator lamps turn OFF. The indoor and

 

 

 

 

[Clean defrost]

outdoor units stop.

 

 

 

 

Defrost is performed

 

 

 

 

 

when the outdoor unit is

 

 

 

 

 

stopped, and the

 

 

 

 

 

 

 

 

 

 

temperature of the

 

 

 

 

 

outdoor unit coil is at or

 

 

 

 

 

below the L1 line.

 

 

 

 

 

(Refer to Fig. 1.)

 

 

 

 

 

 

 

 

 

 

 

Operation is restarted

Starts operating in the same operating mode

Within 4 hours after operation was stopped, it is

 

within 4 hours (only when

(HEAT) and with the same temperature

assumed that there has been no significant

 

AUTO mode is selected

settings as before operation was stopped.

change in the indoor and outdoor temperatures,

 

with the remote

 

and the previous conditions (HEAT) are stored.

 

controller).

 

 

 

 

 

 

 

 

 

 

 

Operation starts after 4

New operation begins based on the

 

 

 

 

hours or more have

temperature conditions at the time the

 

 

 

 

 

 

 

 

passed.

ON/OFF button is pressed.

 

 

 

 

 

 

 

 

 

72

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Panasonic CU-4KE31NBU, CU-4KE24NBU, CU-3KE19NBU service manual Stop
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