Daikin Slim Duct Concealed Indoor Unit FDXS12DVJU

Check the connection of connector

Check motor power supply voltage output (pins 4 - 7)

Check motor control voltage (pins 4 - 3)

Check rotation command voltage output (pins 4 - 2)

Check rotation pulse input (pins 4 - 1)

Conduct the followings to check the outdoor electronic expansion valve (EV).

1. Check to see if the EV connector is correctly inserted in the PCB. Match the EV unit number and the connector number.

2. Turn the power off and on again, and check to see if all the EVs generate latching sound.

3. If any of the EVs does not generate latching sound in the above step 2, disconnect that connector and check the continuity using a tester.

Check the continuity between the pins 1 - 6 and 3 - 6, and between the pins 2 - 5 and 4 - 5. If there is no continuity between the pins, the EV coil is faulty.

4. If no EV generates latching sound in the above step 2, the outdoor unit PCB is faulty.

5. If the continuity is confirmed in the above step 3, mount a good coil (which generated latching sound) in the EV unit that did not generate latching sound, and check to see if that EV generates latching sound.

If latching sound is generated, the outdoor unit PCB is faulty.

If latching sound is not generated, the EV unit is faulty.

Warning: Disconnect the connectors of the thermistors from the PCB before proceeding

Measure the resistance of each thermistor using tester

The relationship between normal temperature and resistance is shown in the table and the graph below

The room temperature thermistor is directly mounted on the display PCB. Remove the display PCB from the control PCB to measure the resistance.

Measure the resistance of the room temperature thermistor

When the indoor heat exchanger thermistor is soldered on the PCB, remove the thermistor and measure the resistance.

Measure the resistance of the indoor heat exchanger thermistor

Sign off on the thermistor resistance check

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 fan motor is operating

Control voltage between the pins 3 - 4

Rotation command voltage between the pins 2 - 4

2 pulses (0 ~ 15 VDC) are output at the pins 1 - 4 when the fan motor is rotated 1 turn by hand