Mitsubishi Electric PQHY-P72TYHMU-A Service Handbook page 254

[ IX Troubleshooting ]
1. Error Code
4102 (YHMU-A)
Open phase
2. Error definition and error detection method
ŒAn open phase of the power supply (L1 phase, L2 phase) was detected at power on.
ŒThe L3 phase current is outside of the specified range.
The open phase of the power supply may not always be detected if a power voltage from another circuit is applied.
3. Cause, check method and remedy
Cause
(1) Power supply problem
ŒOpen phase voltage of the power supply
ŒPower supply voltage drop
(2) Noise filter problem
ŒCoil problem
ŒCircuit board failure
(3) Wiring failure
(4) Blown fuse
(5) CT3 failure
(6) Control board failure
HWE09080
Check method and remedy
Check the input voltage to the power supply terminal block TB1.
ŒCheck the coil connections.
ŒCheck for coil burnout.
ŒCheck that the voltage across TB21 and TB22 on the noise filter
board is 414V or above.
Confirm that the voltage at the control board connector CNAC is
190 V or above.
If the voltage is below 190, check the wiring between noise filter
CN6, noise filter CN2, transformer box, and control board CNAC.
Confirm that the wiring between noise filter TB23 and INV board
SC-L3 is put through CT3.
Check F01 on the control board, F4, and F5 for a blown fuse.
->If a blown fuse is found, check for a short-circuiting or earth fault
of the actuator.
Replace the inverter if this problem is detected after the compres-
sor has gone into operation.
Replace the control board if none of the above is causing the
problem.
- 245 - GB