Sinclair SCV-750EB Service Manual page 75

5.4 E2 Troubleshooting
Digital display output
Description
Communication error between outdoor unit and user interface.
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Communication failure between master and slave units
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All units stop running.
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 Error code is displayed on main PCB and user interface.
Possible causes
Communication wires between outdoor unit and user interface not connected properly.
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For SCV-900EB, Communication wiring P Q E terminals misconnected. For SCV-750EB, SCV-1400EB SCV-1800EB,
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Communication wiring X Y E terminals misconnected
Wiring connection is loosen
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Interference from high voltage wires or other sources of electromagnetic radiation.
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Communication wire too long.
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Damaged main PCB, user interface or electric control box communication terminals block.
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