Daikin Outdoor Unit Standard Multi-Split Type Air Conditioner 2MXS18WMVJU9

Before this check, be sure to check the main circuit for short circuit.

With the circuit breaker still on, measure the voltage according to the drawing of the model in question. Be careful never to touch any live parts.

To prevent an electrical shock, use a multimeter to check that the voltage between FU2 and DC– is 50 V or less.

The surface of the test points (DC–) may be covered with the coating. Be sure to make firm contact between the multimeter probes and the test points.

Before this check, be sure to check the main circuit for short circuit.

With the circuit breaker still on, measure the voltage according to the drawing of the model in question. Be careful never to touch any live parts.

To prevent an electrical shock, use a multimeter to check that the voltage between DC + and DC – is 50 V or less.

Warning: This procedure requires trained personnel with PPE!

Disconnect the connector of thermistor ASSY from the PCB to measure the resistance between the pins using multimeter.

Enter the measured resistance value

Does the measured resistance value match the listed value?

If the measured resistance value does not match the listed value, the thermistor must be replaced.

To check the thermistor soldered on a PCB, disconnect the PCB from other PCB/parts, and measure the resistance between the both ends of soldered thermistor.

Enter the measured resistance value for the soldered thermistor

Does the measured resistance value for the soldered thermistor match the listed value?

Note: When replacing the defective thermistor(s), replace the thermistor as ASSY;

Warning: This procedure requires trained personnel with PPE!

Control voltage between the pins 3 - 4

Rotation command voltage between the pins 2 - 4

4 pulses of sinusoidal voltage detected between pins 1-2

4 pulses of sinusoidal voltage detected between pins 2-3

If NG in step 2 -> Defective PCB -> Replace the outdoor unit PCB (main PCB)

Check to make sure that the voltage between (+) and (–) of the diode bridge (DB1) is about 0 V before checking

Measure the resistance between the pins of the DB1 referring to the table below.

If the resistance is infinity or less than 1 k, short circuit occurs on the main circuit.

2. Remove the top plate (10 screws).

3. Remove the right side plate (6 screws).

4. Remove the front plate (1 screw).

The front plate is heavy, so take care.

Warning: Ensure the voltage between (+) and (–) of the power module is about 0 V before proceeding

Voltage check between (+) and (–) of the power module

Disconnect the compressor harness connector from the outdoor unit PCB

Compressor harness connector disconnected

Measure resistance between the (+) or (–) terminal of the power module and the U, V, or W terminal of the compressor with a multimeter

Enter the resistance measurement

Evaluate the measurement results

Sign off on the power module check