Mitsubishi Electric PURY-P72TYJMU-A Service Handbook page 224

[ IX Troubleshooting ]
1. Error Code
4109
Indoor unit fan operation error
2. Error definition and error detection method
1) During operation, it has been continuously detected for 100 seconds that the auxiliary relay (X13) for fan fault detection is not
excited.
3. Cause, check method and remedy
(1) Auxiliary relay (X13) fault
(2) Connector (CN28) is disconnected.
(3) Blown fuse
(4) Motor error (thermistor error inside the motor)
HWE0913A
Cause
- 215 -
Check method and remedy
Coil failure, disconnected coil
Check the connector for proper connection.
Check the fuse on the control circuit board.
Check the unit fan for proper operation in the test run
mode.
If no problems are found with items 1 through 3 above and
the fan does not operate, replace the motor.
GB