Mitsubishi Electric CITY MULTI PUHY-400YMF-B, Service Handbook, Page: 166 / 204

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Checking code Meaning, detecting method Cause Checking method & Countermeasure
2500
2502
2503
4103
Leakage (water)
abnormality
(Indoor unit)
Drain pump
abnormality
(Indoor unit)
Drain sensor
abnormality
(Indoor unit)
Operation of
float switch
(Indoor unit)
Reverse phase
abnormality
(Outdoor unit)
When drain sensor detects flood-
ing during drain pump OFF.
When indirect heater of drain sen-
sor is turned on, rise in tempera-
ture is 20 deg. or less (in water)
for 40 seconds, compared with the
temperature detected before turn-
ing on the indirect heater.
Short/open is detected during
drain pump operations. (Not de-
tected when drain pump is not
operating.)
Short:
90
°
C or more detected
Open: – 40
°
C or less detected
When float switch operates (point
of contact: OFF), error stop is ob-
served with code No. “2503” dis-
played.
Reverse phase (or open phase)
in the power system is being de-
tected, so operation cannot be
started.
Check water leaking of humidifier and
clogging of drain pan.
Check operations of drain pump.
Measure resistance of indirect heater
of drain sensor.
(Normal: Approx. 82
Ω
between 1-3 of
CN50)
Indoor board trouble if no other prob-
lems is detected.
Check resistance of thermistor.
0
°
C: 15 k
Ω
10
°
C: 9.7 k
Ω
20
°
C: 6.4 k
Ω
30
°
C: 4.3 k
Ω
Check contact of connector.
Indoor port trouble if no other problem
is detected.
Check drain pump operations.
Check connect contact.
Check float switch operations.
If there is reverse phase before the
breaker, after the breaker or at the
power supply terminal blocks TB1 or
TB1A, reconnect the wiring.
Check before the breaker, after the
breaker or at the power supply termi-
nal blocks TB1 or TB1A, and if there is
an open phase, correct the connec-
tions.
a) Check if a wire is disconnected.
b) Check the voltage between each
of the wires.
Check 1 the connections, 2, the con-
tact at the connector, 3, the tightening
torque at screw tightening locations
and 4 for wiring disconnections.
TB1 ~ NF ~ TB1A ~ CNTR1 ~ F3 ~
T01 ~ CNTR
Refer to the circuit number and the
wiring diagram plate.
If F3 or F1 on the MAIN board is
melted, (Resistance between both
ends of the fuse is
∞
), replace the
fuses.
To judge failure of the T01, go to “Indi-
vidual Parts Failure Judgment Meth-
ods.”
If none of the items in 1) to 5) is appli-
cable, and if the trouble reappears
even after the power is switched on
again, replace the MAIN board (when
replacing the circuit board, be sure to
connect all the connectors, etc. se-
curely).
1) Water leak due to humidifier or the
like in trouble.
1) Drain sensor sinks in water because
drain water level rises due to drain
water lifting-up mechanism trouble.
2) Broken wire of indirect heater of drain
sensor.
3) Detecting circuit (circuit board)
trouble.
1) Thermistor trouble.
2) Poor contact of connector.
(insufficient insertion)
3) Full-broken of half-broken thermistor
wire.
4) Indoor unit circuit board (detecting
circuit) trouble.
1) Drain up input trouble.
2) Poor contact of float switch circuit.
3) Float switch trouble.
1) The phases of the power supply (L1,
L2, L3) have been reversed.
2) Open phase has occurred in the
power supply (L1, L2, L3, N).
3) The wiring is faulty.
4) The fuse is faulty.
5) T01 is faulty.
6) The circuit board is faulty.