Daikin Outdoor Unit Air Conditioner RXL18WMVJU9

Warning: This procedure requires trained personnel with PPE!

Disconnect the connector of thermistor ASSY from the PCB to measure the resistance between the pins using multimeter.

Enter the measured resistance value of the thermistor

Does the measured resistance value match the listed value?

To check the thermistor soldered on a PCB, disconnect the PCB from other PCB/parts, and measure the resistance between the both ends of soldered thermistor.

Enter the measured resistance value of the soldered thermistor

Does the measured resistance value of the soldered thermistor match the listed value?

Note: When replacing the defective thermistor(s), replace the thermistor as ASSY.

Sign off on the thermistor resistance check

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

EV connector correctly connected to the PCB

Does the EV generate a latching sound when power is turned off and on again?

If the EV does not generate a latching sound, proceed to the next step

Continuity confirmed using a multimeter after disconnecting the connector

Check the continuity between the following pins

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

If the continuity is confirmed, the outdoor unit PCB (main PCB) is faulty

Sign off on the electronic expansion valve check

Warning: Ensure the circuit is powered off before starting the procedure

Voltage between (+) and (-) of the diode bridge (DB1)

If voltage is not about 0V, stop the procedure and report the issue

Resistance between the pins of the DB1

Is the resistance between the pins of the DB1 either infinity or less than 1 kΩ?

If the resistance is infinity or less than 1 kΩ, a short circuit occurs on the main circuit.

Sign off on the main circuit short check

Ensure that the voltage is within 320 VDC

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 4 - 3 is 15 VDC

Check that the rotation command voltage between the pins 4 - 2 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 4 - 1 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)