Daikin Indoor Unit Ceiling Mounted Cassette Type Heat Pump FFQ15Q2VJU

Warning: Ensure the voltage between (+) and (-) of the diode bridge (DB1) is approximately 0 V before proceeding.

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

Measure the resistance between the pins of the DB1.

Enter the resistance between the pins of the DB1

Is the resistance infinite or less than 1 kΩ?

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

Sign off on the main circuit short check

Warning: This procedure requires trained personnel with PPE!

Install an inverter analyzer instead of a compressor.

Charged voltage of the built-in smoothing electrolytic capacitor dropped to 10 VDC or below?

Terminals from the compressor removed?

Terminals connected to the terminals of the inverter analyzer?

Be careful not to let the terminals (U,V,W) touch each other. Otherwise, high voltage is applied.

Power transistor test operation activated from the outdoor unit?

Diagnose according to 6 LEDs lighting status of the inverter analyzer.

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

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.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).