Mitsubishi Electric PUHY-P72 Service Manual page 184

[ IX Troubleshooting ]
1. Error Code
4230 (THMU-A)
Heatsink overheat protection
2. Error definition and error detection method
When the heat sink temperature (THHS) remains at or above TOH is detected.
Model
P72, P96 models 100°C [212°F]
P120 model
3. Cause, check method and remedy
Cause
(1) Fan board failure
(2) Outdoor unit fan failure
(3) Air passage blockage
(4) THHS failure
Refer to section -6- "Inverter (THMU-A)" under part [4] Troubleshooting Principal Parts for error codes related to the
inverter.(page 244)
HWE0804A
TOH
90°C [194°F]
Refer to IX [4] -6- (2) [6].(page 247)
Check the outdoor unit fan operation.
If any problem is found with the fan operation, check the fan motor. ->Refer to
IX [4] -6- (2) [5].(page 247)
Check that the heat sink cooling air passage is not blocked
P72 and P96 models
1) Check for proper installation of the INV board IGBT. (Check for proper instal-
lation of the IGBT heatsink.)
2) Check for proper installation of the INV board IGBT.
->If an abnormal value appears, replace the INV board.
P120 model
3) Check the THHS sensor reading on the LED monitor.
->If an abnormal value appears, check the sensor resistance, and replace the
sensor as necessary.
Check method and remedy
- 175 - GB