Mitsubishi Electric HP120TNU-A Service Handbook page 183

[7-5 Error Code Definitions and Solutions: Codes [3000 - 3999] ]
7-5-3 Error Code [3512]
1. Error code definition
Cooling fan locking
2. Error definition and error detection method
The motor on the cooling fan locks during operation.
3. Cause, check method and remedy
Cause
(1) Locked cooling fan motor
(2) Cooling fan motor trouble
(3) Contact failure
(4) Circuit board fault
20
- chapter 7
Check method and remedy
Check the fan blades for objects obstructing the rotation of
the cooling fan.
Disconnect the wiring from the cooling fan motor, and check
the insulation resistance and the coil resistance of the motor.
Replace the motor if problems are found.
Criteria for insulation failure: Insulation failure if below 1 M
Wire disconnection: Normal if coil resistance is between 56
and 65
Check the wiring between CN101 and CN63PW.
Check the wiring between CN24V and RY24V.
Check the RY24V terminal block for problems.
If no problems are found with the items above, replace the
control board and the PS board.
HWE18220_GB