Heat Pump, Split System, Single Service, 3 phase
Maintenance Document 1394-1 27
Clear 2: Serial forward transfer error
Hydraulic Unit LED:
Green 1 flash / Red 1 flash
Outdoor Unit LED: 1 flash
Probable causes:
• Misconnection.
• External cause.
• Interface PCB failure.
Check:
1-1. Stop the system and start it again (disconnection time 1min):
Is the error still displayed?
YES NO
3. Check the power supply voltage:
- Check that an AC 198 – 264 V voltage exists between terminals 1 and 2,
L1 and N, L2 and N, L3 and N on the outdoor unit terminal block.
OK
4. Check the serial signal:
- Check the voltage between terminals 2 and 3 of the outdoor terminal block. The
voltage must fluctuate between AC 70 V and AC 130 V.
- If it doesn't, replace Interface PCB.
OK
1-2. Check for external causes:
- Check the system's overall isolation.
- Check for any equipment generating
electromagnetic waves which interfere with the
communication between the hydraulic unit and the
outdoor unit.
2. Check the connections:
- Check the connection between the hydraulic
unit and the outdoor unit.
- Check the connections between the outdoor
unit main board and the active filter board.
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