Daikin Indoor Unit Multi-Split Type Air Conditioner CTXG09QVJUS

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

If the room temperature thermistor is soldered on a PCB, remove the PCB from the control PCB to measure the resistance

Room temperature thermistor removed from the PCB

Measure the resistance of the room temperature thermistor

If the connector of indoor heat exchanger thermistor is soldered on a PCB, remove the thermistor and measure the resistance

Indoor heat exchanger thermistor removed from the PCB

Measure the resistance of the indoor heat exchanger thermistor

EV connector correctly inserted in the PCB

All EVs generate a latching sound after power cycle

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

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

If no EV generates a latching sound, the outdoor unit PCB is faulty

With the power on, operation off, and the connector connected, check the following

Output voltage of about 5 V between pins 1 and 3

Generation of 3 pulses between pins 2 and 3 when the indoor fan motor is operating

If NG in step (1) -> Defective PCB -> Replace the PCB (control PCB)

If NG in step (2) -> Defective Hall IC -> Replace the indoor fan motor

If OK in both steps (1) and (2) -> Replace the PCB (control PCB)

Warning: Ensure the voltage between (+) and (–) of the diode bridge (DB1) is about 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

Is the resistance ∞ or less than 1 kΩ?

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

Sign off on the main circuit short check

Warning: This check requires trained personnel with PPE!

Measure the power supply waveform between No. 1 and No. 2 on the terminal board

Upload a photo of the measured waveform

Is the power supply waveform a sine wave (Fig.1)?

Is there waveform disturbance near the zero-cross (sections circled in Fig.2)?

Sign off on the power supply waveform check