Fujitsu Comfort Series Service Manual page 25

Troubleshooting 4
HYDRAULIC UNIT Error Method:
UART communication error
Detective Actuators:
Hydraulic unit Interface PCB
Hydraulic unit Main PCB
Forecast of Cause:
1. Connection failure
Check Point 1-1 : Reset the power and operate
Does Error indication show again?
YES YES
Check Point 2 : Check Connection
Check any loose or removed connector between
Main PCB in Hydraulic unit and Interface PCB.
>> If it doesn't work, replace the connector between
Main PCB and Interface PCB.
>> If it doesn't work, replace the Main PCB and
Interface PCB.
Indicate or Display:
Hydraulic unit :
Green Red
3 2
n : n times blinking
Detective details:
When the UART connection fails for 25 seconds.
2. External cause 3. Main PCB failure
NO
Check Point 1-2: Check external cause such as noise
03-06
Outdoor unit : No indication
4. Interface PCB failure
Check the complete insulation of the grounding.
Check if there is any equipment that causes harmonic wave
near the Hydraulic unit (Neon light bulb or any electronic
equipment which causes harmonic wave).