Question about Heating & Cooling
Error U4 on your unit means Failure of transmission between indoor and outdoor unit.
the probable reasons for this would be
Indoor to outdoor, outdoor to outdoor transmission wiring F1, F2 disconnection, short circuit or
Outdoor unit power supply is OFF
System address doesn’t match
Defect of indoor unit PC board
Defect of outdoor unit PC board
to me it Sounds like an interconnecting wiring error. Check wiring connection i.e. wires are connected in right order 1 to1 2 to 2 etc. from indoor terminal board to outdoor terminal board. Also check for slack or loose connections.
However U4 code on the daikin means outdoor PCB is faulty and needs to be replaced.. and LED A not lighting also indicates faulty outoor pcb.
So give both the above conditions a check. you should be all set to go.....
Please please take necessary safety precaution before you try testing the unit yourself.... If you are least bit uncomfortable about what you are going to do... please do not hesitate to call for a technician.......
Good Luck with your fixya
Posted on Jul 31, 2010
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Posted on Jan 02, 2017
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