Daikin Outdoor Unit Wall Mounted Type Air Conditioner RX25K5V1B

Warning: Ensure the voltage between (+) and (–) of the power module is about 0 V before proceeding

Disconnect the compressor harness connector from the outdoor unit PCB. To disengage the connector, press the protrusion on the connector.

Connector disengaged successfully?

Measure resistance between the terminals of the power module and the terminals of the compressor with a multimeter.

Enter the resistance measurement

Evaluate the measurement results

Sign off on the power module check

Warning: Disconnect the connectors of the thermistors from the PCB before proceeding

Thermistors disconnected from the PCB?

Measure the resistance of each thermistor using a multimeter

If the room temperature thermistor is soldered on a PCB, remove the PCB from the control PCB to measure the resistance

Room temperature thermistor removed from the PCB?

Measure the resistance of the room temperature thermistor

If the connector of indoor heat exchanger thermistor is soldered on a PCB, remove the thermistor and measure the resistance

Indoor heat exchanger thermistor removed from the PCB?

Measure the resistance of the indoor heat exchanger thermistor

Warning: This procedure requires trained personnel with PPE!

Install an inverter analyzer instead of a compressor.

Charged voltage of the built-in smoothing electrolytic capacitor dropped to 10 VDC or below?

Terminals removed from the compressor?

Terminals connected to the terminals of the inverter analyzer?

Warning: Be careful not to let the terminals (U,V,W) touch each other. Otherwise, high voltage is applied.

Power transistor test operation activated from the indoor unit?

Diagnose method (Diagnose according to 6 LEDs lighting status.)

Warning: This check requires trained personnel with PPE!

Enter the power supply waveform measurement between No. 1 and No. 2 on the terminal board

Is the power supply waveform a sine wave as shown in Fig.1?

Is there waveform disturbance near the zero-cross as shown in the sections circled in Fig.2?

Upload a photo of the measured waveform

Sign off on the power supply waveforms check

Ensure that the voltage of 320 + 100 V ~ 320 - 50 V is applied

Set operation off and power off. Disconnect the connector S70 or S71

Check that the voltage between the pins 4 - 7 is 320 VDC

Check that the control voltage between the pins 3 - 4 is 15 VDC

Check that the rotation command voltage between the pins 2 - 4 is 0 ~ 6.5 VDC

Keep operation off and power off. Connect the connector S70 or S71

Check whether 4 rotation pulses (0 ~ 15 VDC) are input at the pins 1 - 4 when the fan motor is rotated 1 turn by hand

When the fuse is melted, check the outdoor fan motor for proper function

If NG in step 2 → Defective PCB → Replace the outdoor unit PCB (main PCB)