Mitsubishi Electric CITY MULTI PUHY-400YMF-C Service Handbook page 160

Checking code Meaning, detecting method
2500 Leakage (water)
When drain sensor detects flood-
abnormality
ing during drain pump OFF.
2502 Drain pump
When indirect heater of drain sen-
abnormality
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.
2503 Drain sensor
Short/open is detected during drain
abnormality
pump operations. (Not detected
when drain pump is not operating.)
Short:
Open:
Operation of
When float switch operates (point
float switch
of contact : OFF), error stop is ob-
served with code No. "2503" dis-
played.
4103 Reverse phase Reverse phase (or open phase) in
abnormality the power system is being de-
tected, so operation cannot be
started.
1) Water leak due to humidifier or the
like in trouble.
1) Drain sensor sinks in water be-
cause 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 ther-
90˚C or more detected
-40˚C or less detected mistor 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.
Cause
-157-
Checking method & Countermeasure
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 between 1-3 of
CN50)
Indoor board trouble if no other
problems is detected.
Check resistance of thermistor.
0˚C : 15k 10˚C : 9.7k
20˚C : 6.4k 30˚C : 4.3k
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 TB1A,
reconnect the wiring.
Check before the breaker, after the
breaker or at the power supply termi-
nal blocks TB1A, and if there is an open
phase, correct the connections.
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.
TB1A~NF~TB1B~CNTR1~F3~
T01~CNTR
Refer to the circuit number and the wir-
ing diagram plate.
If F1 on the MAIN board, or F3 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 replac-
ing the circuit board, be sure to con-
nect all the connectors, etc. securely).