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Thread: daikin u4 fault
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22-08-2016, 06:55 PM #1
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daikin u4 fault
system details RZQ71B9V3B1 CONNECTED TO TWO FFQ35B8VIB Cassetts
Age 10 yrs
After about 8hrs running the system goes into U4 fault, when in U4 fault one of the fan coil fans runs.
service history no faults system serviced twice yr from new
When in fault LED lights on cassettes flash
Green LED GH HAP on condensing unit flashes
have disconnected terminal three from condensing unit and disconnected terminal three from both fan coil, there was a 1.9dcv on first fan coil and a 2.1dcv on fan coil two.
there is no external condense pump fitted to this system.
Help needed please
David
[Edit - thread moved from 'refrigerants' as it was not the topic of this post.]Last edited by Brian_UK; 22-08-2016 at 10:48 PM.
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22-08-2016, 10:47 PM #2
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Re: daikin u4 fault
Have you checked the interconnecting wiring?
There may be a defective indoor pcb.Brian - Newton Abbot, Devon, UK
Retired March 2015
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23-08-2016, 09:31 PM #3
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Re: daikin u4 fault
Is terminal 3 only connected on one indoor unit, not both? used to be the case on other brands.
Mostly found in the southern part of this green and pleasant land.
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24-08-2016, 02:15 AM #4
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Re: daikin u4 fault
I would also check the fan motor. Sometimes a faulty fan motor can cause a U4 fault.
Unplug it and start the unit, See if it runs ok for a little bit then it will fault out on fan motor missing fault. If U4 occurs then you may still have a faulty indoor PCB or interconnects
