Error Codes: System Malfunctions
ESIE13-02
Part 4 – Troubleshooting
144
3
1
4
5
5.4
“U4”
Malfunction of Transmission between Hydro-box and Outdoor Unit
Remote controller
display
U4
Error generation
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.
Supposed causes
The possible causes are:
Wiring indoor-outdoor transmission wire is incorrect
Malfunctioning hydro-box PCB
Malfunctioning outdoor unit PCB
Outside cause (noise...).
Troubleshooting
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.
NO
YES
Is the power
supply voltage between
180 and 220 VAC?
YES
NO
NO
NO
Wire correctly and securely
fasten the terminal screws.
Replace fuse. Use only
specified fuses.
Field factor
Replace the outdoor
fan motor.
Is there
miswiring, a
wrong wire type,
loose terminal or contact
failure in the inter-unit wiring
between the hydro-box
and outdoor
units?
(*)
YES
Is HAP on the
outdoor PC board blinking?
(Outdoor PC
board)
YES
Is HAP
blinking? (Outdoor PC
board)
B
Turn OFF the power supply and
disconnect the connector of the
outdoor fan motor.
Then power ON again.
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?
