Daikin Outdoor Unit For VRV System R24NUV2S

Check for Fan Motor Connector (Signal Line)

(2) With the fan motor connector disconnected, measure the resistance between each pin, then make sure that the resistance is more than the value mentioned in the following table.

(2) With the fan motor connector disconnected, measure the resistance between each pin, then make sure that the resistance is balanced in ±30%.

Check for Fan Motor Connector (Power Supply Line)

With the relay connector disconnected, measure the resistance between UVW phases of the connector (3 cores) at the motor side, then make sure that the resistance between each phase is balanced and not short-circuited.;

Warning: Do not touch the energized part (high voltage part) for at least 10 minutes after the power is turned OFF.

Be sure to touch the earth terminal with a hand to release static electricity from the body (to prevent PCB from being damaged).

Residual electric charge of the power transistor (should be DC 50V or less)

Remove the connector of the outdoor unit fan motor.

Remove the wire connecting the power transistor and the compressor. Remove it from the compressor terminal side.

During this work, be careful not to deform. Faston terminal at the end of the relay wire.

Measure resistance using an analog tester

Fill in the blanks in the following table

Diagnosis of inadequate refrigerant in cooling operation

Suction superheated degree increases due to refrigerant shortage

Decreased evaporator capacity caused by refrigerant shortage

Compressor frequency decreases despite a large difference between temperature set by the remote controller and suction air temperature

If refrigerant shortage worsens, the electronic expansion valve remains fully open and suction superheated degree further increases

Diagnosis of inadequate refrigerant in heating operation

Suction superheated degree increases due to refrigerant shortage in heating operation

Compressor frequency decreases because suction superheated degree is controlled to prevent oil to the outdoor unit heat exchanger from being retained

Evaporator capacity and compressor frequency decrease despite a large difference between temperature set by the remote controller and suction air temperature

Warning: Disconnect the thermistor from the PCB before proceeding

Thermistor disconnected from the PCB

Temperature reading from the thermistor

Resistor value from the thermistor

Check if the measured values correspond with the values in the table

Sign off on the thermistor check

Warning: This check requires trained personnel with PPE!

Enter the current pressure level

Is the pressure level above the normal range?

If pressure is above normal range, proceed with the following checks

Select the most likely cause of high pressure

Upload a photo of the suspected part

Sign off on the high pressure check