Mitsubishi PWFY-P36NMU-E-BU Service Handbook page 72

-5- Inverter
Replace only the compressor if only the compressor is found to be defective.
Replace the defective components if the inverter is found to be defective.
If both the compressor and the inverter are found to be defective, replace the defective component(s) of both devices.
(1) Inverter-related problems: Troubleshooting and remedies
1) The inverter board has a large-capacity electrolytic capacitor, in which residual voltage remains even after the main power is
turned off, posing a risk of electric shock. Before inspecting the inside of the control box, turn off the power, leave the unit
turned off for at least 10 minutes, and check that the voltage between the pins of CN631 has dropped to 20V or less.
(It takes about 10 minutes to discharge electricity after the power supply is turn off.)
2) If cables are not inserted properly to the Faston terminals or connectors are not connected properly, inverter parts will be
damaged. If a problem occurs after replacing some of the parts, mixed up wiring is often the cause of the problem. Check for
proper connection of the wiring, screws, connectors, and Faston terminals.
3) To avoid damage to the circuit board, do not connect or disconnect the inverter-related connectors with the main power
turned on.
4) Faston terminals have a locking function. Make sure the terminals are securely locked in place after insertion. Press the
tab in the middle of the terminals to remove them.
5) When replacing the INV (inverter) board, apply a thin layer of grease (supplied with the service parts) evenly to the
radiation plate. Wipe off any grease that may get on the wiring terminal to avoid terminal contact failure.
6) Faulty wiring to the compressor damages the compressor. Connect the wiring in the correct phase sequence.
Squeeze down with your finger
Plastic tab
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Cable