U4" Malfunction Of Transmission Between Hydro-Box And Outdoor Unit - Daikin ESIE13-02 Service Manual

Error Codes: System Malfunctions

"U4" Malfunction of Transmission between Hydro-box and Outdoor Unit

5.4
1
Remote controller
display
Error generation
Supposed causes
3
Troubleshooting
4
5
Part 4 – Troubleshooting
U4
The error is generated when the microprocessor detects that the transmission between the indoor and
the outdoor unit is not normal over a certain amount of time.
The possible causes are:
Wiring indoor-outdoor transmission wire is incorrect

Malfunctioning hydro-box PCB

Malfunctioning outdoor unit PCB

Outside cause (noise...).

Diagnosis of incorrect or broken/disconnected wiring. If the LEDs on the hydro-box PC board are off,
it indicates that the transmission wiring between indoor and outdoor units may be incorrect or
broken/disconnected.
Is the power
supply voltage between
180 and 220 VAC?
Is there
miswiring, a
wrong wire type,
loose terminal or contact
failure in the inter-unit wiring
between the hydro-box
and outdoor
units?
(*)
Is HAP on the
outdoor PC board blinking?
(Outdoor PC
board)
Turn OFF the power supply and
disconnect the connector of the
outdoor fan motor.
Then power ON again.
Is HAP
blinking? (Outdoor PC
board)
A
(*) ERHQ***V3* / ERLQ***V3*
Does the fuse F3U on the communicator PC board (A4P) have No continuity?
ERHQ***W1* / ERLQ***W1*
Does the fuse F6U on the control PC board (A1P) have No continuity?
NO
YES
YES
NO
YES
NO
YES
NO
144
ESIE13-02
Field factor
Wire correctly and securely
fasten the terminal screws.
Replace fuse. Use only
specified fuses.
B
Replace the outdoor
fan motor.