Fujitsu AUUH18LUAS Service Manual page 74

Check point 4. Check serial signal (Forward transfer signal)
Check serial signal (Forward transfer signal)
• Check if indicated value swings between AC 30 V and AC 130 V at outdoor unit terminal 2—3.
• If it is abnormal, replace main PCB.
Check point 1-2. Check external cause such as noise
• Check the complete insulation of the grounding.
• Check if there is any equipment that causes harmonic wave near the power cable (Neon light
bulb or any electronic equipment which causes harmonic wave).
2-2. E: 11.↓. Serial communication error (Serial forward transfer error) (Indoor unit)
BLACK
1
WHITE 2
3
RED
BLACK
L1
WHITE L2
End
End
+
-
- (03-8) -
2. Troubleshooting with error code