8-3. Checking the Outdoor System

8-3-1. Checking the outdoor unit

No.

Work procedure

Check items (unit operation)

 

 

 

1

• Apply 220 V AC between terminals L1 and L2 on the

• The LED (red) on the control board must illuminate.

 

outdoor unit terminal plate.

 

 

 

 

2

Short-circuit the T-RUN terminal to the COM terminal

• The compressor, fan motor, 4-way valve, and solenoid

 

of TEST/T-RUN terminals.

valve (for the hot gas bypass) must turn ON.

 

 

(They turn ON about (70) seconds later after the power

 

 

is turned ON.)

 

 

 

NOTE If the above check items are okay, but the outdoor unit does not operate, there may be a faulty connection between the indoor unit and the outdoor unit.

8-3-2. Checking the defrost operation

Using forced defrost operation to check this function.

No.

Work procedure

 

Check items (unit operation)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

• Connect a dummy resistor of 39 k ohm to the outdoor

 

Non-stop defrost

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

coil temperature sensor connector.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

30 sec.

 

 

 

 

 

 

 

 

 

 

 

 

Indoor fan

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Setting

LL

Stop

 

 

 

 

 

 

Setting

 

 

 

CM

 

 

 

 

 

 

 

 

(80 Hz)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ON

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Solenoid valve

 

 

5 sec.

 

 

 

 

 

 

 

10 sec.

 

 

 

(for hot gas

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

bypass) OFF

 

 

 

 

ON

 

 

 

 

 

 

OFF

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Outdoor fan

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ON

 

 

 

 

 

OFF

 

 

 

 

 

 

ON

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Defrost start

Release

• The maximum length of defrost operation is 12 minutes.

Defrost can also be released based on the below conditions for the outdoor heat exchanger sensor.

Less than 2 minutes Not released

2 minutes or more 57.2 °F or higher (*1)

*1 However, the condition is (68 °F) or higher when the outdoor air temperature is below 32 °F.

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Panasonic CU-4KE24NBU, CU-4KE31NBU Checking the Outdoor System, Checking the outdoor unit, Checking the defrost operation

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