Mitsubishi Electric PUHY-HP72 Service Handbook page 150

[7-6 Error Code Definitions and Solutions: Codes [4000 - 4999] ]
7-6-14 Error Code [4220] Detail Code 129
1. Error code definition
Control power supply error (Detail code 129)(outdoor unit)
2. Error definition and error detection method
INV42Y and INV38
Detection of insufficient drive voltage for relays on INV board
3. Cause, check method and remedy
Cause
(1) Contact failure
(2) Voltage check
(3) Inverter board failure
For inverter-related error codes, refer to the following page(s). [8-9 Troubleshooting Inverter Problems]
7-6-15 Error Codes [4220, 4225, 4226] Detail Code 131
1. Error code definition
Low bus voltage at startup (Detail code 131) (YNU)
2. Error definition and error detection method
When Vdc 289 V is detected just before the inverter operation. (YNU)
3. Cause, check method and remedy
(1) Inverter main circuit failure
Same as detail code 108 of 4220 error
For inverter-related error codes, refer to the following page(s). [8-9 Troubleshooting Inverter Problems]
7-6-16 Error Codes [4220, 4225, 4226] Detail Code 131
1. Error code definition
Low bus voltage at startup (Detail code 131) (TNU)
2. Error definition and error detection method
When Vdc 160 V is detected just before the inverter operation. (TNU)
3. Cause, check method and remedy
(1) Inverter main circuit failure
Same as detail code 108 of 4220 error
For inverter-related error codes, refer to the following page(s). [8-9 Troubleshooting Inverter Problems]
HWE18240_GB
Check method and remedy
<INV42Y and INV38>
Check the connectors CNRY on INV board and CNRYA on MAIN board for proper
connections.
Disconnect the connector CNRYA from the control board and check the voltage at
the connector CNRYA. If a voltage of 13 V is not output, replace the control board
and the PS board.
If the problem persists after reboot, replace the INV board.
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