Table of Contents
[8-10 Troubleshooting Inverter Problems ]
8-10 Troubleshooting Inverter Problems
8-10-1
Inverter-Related Problems and Solutions
Replace only the compressor if only the compressor is found to be defective. (Overcurrent will flow through the inverter if the
compressor is damaged, however, the power supply is automatically cut when overcurrent is detected, protecting the inverter
from damage. Make sure that the model selection switches on the outdoor unit (Dip switches SW5-3 through 5-8 on the out-
door unit control board) are set correctly. For switch settings, refer to the following page(s). [7-9-2 Error Code [7101]](page
286))
Replace only the fan motor if only the fan motor is found to be defective. (Overcurrent will flow through the inverter if the fan
motor is damaged, however, the power supply is automatically cut when overcurrrent is detected, protecting the inverter from
damage.)
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) Inside the inverter is a large capacity electrolytic capacitor, and the residual voltage that remains after the main power is turned
off presents 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 across FT-P and FT-N terminals or SC-P and SC-N terminals on the
inverter board has dropped to 20 VDC or less. (It takes approximately 10 minutes to discharge electricity after the power is
turned off.)
2) Before starting maintenance work, disconnect the connector (CNINV) on the outdoor unit fan board and CN1 on the inverter
board (or CNFAN2 on the capacitor board). Before connecting or disconnecting connectors, make sure that the outdoor unit
fans are stopped and that the voltage of the main circuit capacitor is 20 VDC or below. If the outdoor unit fan is turned by
strong winds, the main circuit capacitor will be energized and poses an electric shock hazard. Refer to the wiring diagram
name plate for details.
3) To connect wiring to TB7, check that the voltage is 20 VDC or below.
4) After completion of maintenance work, reconnect the connector (CNINV) on the fan board and connector (CN1) on the inverter
board (or the connector (CNFAN2) on the capacitor board).
5) The IPM on the inverter becomes damaged if there are loose screws are connectors. 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.
6) To avoid damage to the circuit board, do not connect or disconnect the inverter-related connectors with the main power turned
on.
7) Faston terminals have a locking function. Make sure the terminals are securely locked in place after insertion.
8) When the IPM or IGBT is replaced, apply a thin layer of heat radiation grease that is supplied evenly to these parts. Wipe off
any grease that may get on the wiring terminal to avoid terminal contact failure.
9) Faulty wiring to the compressor damages the compressor. Connect the wiring in the correct phase sequence.
10) When the power is turned on, the compressor and the heater are energized even while they are not operating. Before turning
on the power, disconnect all power supply wires from the compressor terminal block, and measure the insulation resistance
of the compressor. Check the compressor for a ground fault. If the insulation resistance is 1.0 MΩ or below, connect all power
supply wires to the compressor or the heater, and turn on the power to the outdoor unit. (The liquid refrigerant in the compres-
sor will evaporate by energizing the compressor.)
HWE1314A
Press the tab on the terminals to remove them.
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GB
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