Daikin Outdoor Heat Pump RXL18UMVJUA

Warning: Ensure the voltage between (+) and (–) of the diode bridge (DB1) is about 0 V before proceeding

Enter the voltage between (+) and (–) of the diode bridge (DB1)

Measure the resistance between the pins of the DB1 referring to the table below.

Enter the resistance between the pins of the DB1

Is the resistance infinity or less than 1 k(omega)?

If the resistance is infinity or less than 1 k(omega), short circuit occurs on the main circuit.

Sign off on the main circuit short check

Warning: Disconnect the connector of thermistor ASSY from the PCB before proceeding

Enter the resistance value measured from the thermistor

Does the measured resistance value match the listed value?

If the measured resistance value does not match the listed value, the thermistor must be replaced.

To check the thermistor soldered on a PCB, disconnect the PCB from other PCB/parts

Enter the resistance value measured from the soldered thermistor

Does the measured resistance value match the listed value?

If the measured resistance value does not match the listed value, the thermistor must be replaced.

Sign off on the thermistor resistance check

If an abnormal stop occurs due to compressor startup failure or overcurrent output when using an inverter unit, it is difficult to judge whether the stop is caused by the compressor failure or some other failure (main PCB, power module, etc.). The inverter analyzer makes it possible to judge the cause of trouble easily and securely. Connect an inverter analyzer as a quasi-compressor instead of compressor and check the output of the inverter.

Step 1: Be sure to turn the power off.

Step 2: Install an inverter analyzer instead of a compressor.

Note: Make sure the charged voltage of the built-in smoothing electrolytic capacitor drops to 10 VDC or below before carrying out the service work.

(1) Remove the terminals from the compressor.

(2) Connect the terminals to the terminals of the inverter analyzer.

Warning: This check requires trained personnel with PPE!

Measure the power supply waveform between No. 1 and No. 2 on the terminal strip

Upload a photo of the measured waveform

Is the power supply waveform a sine wave?

Is there waveform disturbance near the zero-cross?

Sign off on the power supply waveform check

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

Control voltage between the pins 4 - 3

Rotation command voltage between the pins 4 - 2

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

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

Outdoor fan motor functioning properly?