Daikin Outdoor Unit Heat Pump For Split System RXS25L3V1B

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

Thermistors disconnected from the PCB

Measure the resistance of the room temperature thermistor using multimeter

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

PCB removed from the control PCB

Measure the resistance of the room temperature thermistor after removing the PCB

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 after removing it from the PCB

1. Check the connector connection.

2. With the power on, operation off, and the connector connected, check the following.

(1) Output voltage of about 5 V between pins 1 and 3.

(2) Generation of 3 pulses between pins 2 and 3 when the fan motor is operating.

If NG in step (1) => Defective PCB => Replace the PCB (control PCB).

If NG in step (2) => Defective Hall IC => Replace the fan motor.

If OK in both steps (1) and (2) => Replace the PCB (control PCB).;

EV connector correctly connected to the PCB

EV generates a latching sound when power is turned off and on again

Continuity confirmed when connector is disconnected and checked with a multimeter

Check the continuity between the pins

If there is no continuity between the pins, the EV coil is faulty

If the continuity is confirmed, the outdoor unit PCB is faulty

Sign off on the electronic expansion valve check

Warning: This check requires trained personnel with PPE!

Is the power supply waveform between No. 1 and No. 2 on the terminal board a sine wave?

Upload a photo of the waveform (Fig.1)

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

Upload a photo of the waveform disturbance (Fig.2)

Sign off on the power supply waveforms check

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

Voltage between (+) and (–) of the power module is about 0 V

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

Compressor harness connector disconnected from the outdoor unit PCB

Follow the procedure below to measure resistance between the terminals of the power module and the terminals of the compressor with a multimeter.

Enter the resistance measurement between the terminals of the power module and the terminals of the compressor

Evaluate the measurement results

Sign off on the power module check