Quote Originally Posted by airconengineer
the outdoor model No is
RR71B7V3B

thanks for the quick response
Single phase non-inverter compressor.
U4 code on the daikin means outdoor PCB.
Incorrect. U4 means that the indoor unit cannot communicate with the outdoor unit.
Changed the pcb but the fuse blew straight away.
Doh!
the pcb is fine what do i do now


Are you now saying that the outdoor pcb LED is flashing (green one) and the U4 fault has gone? is the only fault code now EO?

Have you carefully checked the connectors on the new pcb (the grey ones)? Does the system run first then fault with EO or refuse to run?

If it refuses to run from cold and just shows an EO then I would suspect that you have got a wiring problem. Pull off the grey wire connectors and check for continuity (through the fan and compressor). If you have continuity here then it may be that the connectors are not seated correctly or are on the wrong pins