Daikin Outdoor Unit Ceiling Mounted Cassette Type Heat Pump RX12QMVJU

Warning: Ensure the voltage between (+) and (-) of the power module is approximately 0 V before proceeding.

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

Measure resistance between the terminals of the power module

Measure resistance between the terminals of the compressor

Evaluate the measurement results

Sign off on the power module check

Check No.16: Make sure that the voltage is within 320 VDC.

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

2. Check that the voltage between the pins 4 - 7 is 320 VDC.

3. Check that the control voltage between the pins 4 - 3 is 15 VDC.

4. Check that the rotation command voltage between the pins 4 - 2 is 0 ~ 6.5 VDC.

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

6. 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).

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: This procedure requires trained personnel with PPE!

If power is not turned off, turn it off before proceeding

Is the inverter analyzer installed instead of a compressor?

If not, install the inverter analyzer instead of a compressor

Is the charged voltage of the built-in smoothing electrolytic capacitor 10 VDC or below?

If not, wait until the charged voltage drops to 10 VDC or below

Are the terminals (U,V,W) not touching each other?

If they are touching, adjust them so they are not touching

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