Mitsubishi Electric CITY MULTI PUHY-P108 Service Handbook page 285

[ IX Troubleshooting ]
Error Code
2503 Drain sensor
failure
2600 Water leakage
2601 Water supply
cut-off
4103 Reverse
phase/open
phase
Error definition and error
detection method
When a short or an open (1) Thermistor failure
is detected during opera- (2) Connector contact failure
tion (cannot be detected
during OFF). (3) Disconnected wire or par-
Short :
detectable at 90°C
[194°F] or higher
Indoor board (detection circuit)
Open :
failure
detectable at
-20°C [-4°F] or lower
- Water leaks from the pipes in
such as the humidifier.
- (1) The water tank of the hu-
(2) The solenoid valve for hu-
(3) Disconnected float switch
(4) Poor operation of float
(5) Frozen water tank
1. When turning on the (1) Faulty wiring
power, the operation
cannot be started be-
cause of the open
phase of one of the
power lines (L1, L2 or
L3).
(2) Main board failure
2. The operation cannot (1) Power supply error
be started because of
the reserve phase of
one of the power lines
(L1, L2 or L3).
(2) Faulty wiring
(3) A fuse is blown.
(4) Main board failure
Cause
(loose connector)
tial disconnected ther-
mistor wire
midifier is empty.
midification is OFF.
switch
Open phase of power
supply voltage
Power-supply voltage
drop
Between the power supply
terminal block (TB1) and
the main boards (CN20
and 21)
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Check method and remedy
Check the thermistor resistance.
0°C [32°F] : 6.0 kohm
10°C [50°F] : 3.9 kohm
20°C [68°F] : 2.6 kohm
30°C [86°F] : 1.8 kohm
40°C [104°F] : 1.3 kohm
Check the connector contact.
If no fault is found, the indoor board
is a failure.
Check the location of the leak.
Check the amount of supply water.
Check for the solenoid valve and for
the connection.
Check the connector.
Check the connecting part.
Check for the float switch.
Turn off the power source of the wa-
ter tank to defrost, and turn it on
again.
Check whether the phase of the
power supply terminal block (TB1)
is normal.
Check the wiring between the pow-
er supply terminal block (TB1) and
the main boards (CN20 and
CN21).
TB1 Pin
L1 CN20 5Pin
L2 CN21 3Pin
L3 CN21 1Pin
If the above faults are not found, the
main board is faulty.
Check the input resistance of the
power supply terminal block (TB1).
Measure voltages of pin 5 of the
male connector (CN20) on the
main board and between pins 1
and 3 of the male connector
(CN21) on the main board.
If the voltage is not the same as the
power supply voltage, the wiring is
faulty.
Check whether the fuses of the main
board (both F01 and F02) are not
blown.
If the above faults are not found, the
main board is faulty.