Daikin Outdoor Unit Ceiling Mounted Cassette Type Heat Pump RX12RMVJU9

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 short circuit occur on the main circuit?

Sign off on the main circuit short 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: Ensure operation is off and power is off before starting the procedure.

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?

EV connector correctly connected to the PCB

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

Continuity check using a multimeter after disconnecting the connector if no latching sound is generated

Check the continuity between the pins

EV coil fault if no continuity between the pins

Outdoor unit PCB (main PCB) fault if continuity is confirmed

Sign off on the electronic expansion valve check

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

Note: The data is for reference purpose only

Is the room temperature thermistor soldered on a PCB?

If yes, remove the PCB from the control PCB to measure the resistance

Is the connector of indoor heat exchanger thermistor soldered on a PCB?

If yes, remove the thermistor and measure the resistance

Measure the resistance of the indoor heat exchanger thermistor