Daikin Outdoor Unit Ceiling Mounted Cassette Type Heat Pump RX12RMVJU

Check No.20: Check to make sure that the voltage between (+) and (–) of the diode bridge (DB1) is approximately 0 V before checking.

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

If the resistance is  or less than 1 k, does a short circuit occur on the main circuit?

Sign off on the main circuit short check

EV connector correctly connected to the PCB

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

Continuity present when connector is disconnected and checked with a multimeter

Check the continuity between the pins

Outdoor unit PCB (main PCB) is not faulty

Sign off on the electronic expansion valve check

Check No.22: Make sure that the voltage between (+) and (–) of the power module is approximately 0 V before checking.

Voltage between (+) and (–) of the power module is approximately 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

Check the connection of connector

Check motor power supply voltage output (pins 5 ~ 8)

Check motor control voltage (pins 5 ~ 4)

Check rotation command voltage output (pins 5 ~ 3)

Check rotation pulse input (pins 5 - 2)

Sign off on the connector output 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

Note: The data is for reference purpose only

Room temperature thermistor removed from the control PCB

Measure the resistance of the room temperature thermistor

Indoor heat exchanger thermistor removed

Measure the resistance of the indoor heat exchanger thermistor

Sign off on the thermistor resistance check