Mitsubishi Electric CITY MULTI PUHY-80TMU-A Service Handbook page 66

Checking code Meaning, detecting method
1.
1111 Low When saturation tempera-
pressure
ture sensor (TH2) detects
satura-
–40°C or less (the first time)
tion
during operations, out-
tempera-
door unit stops once,
ture
mode is changed to restart
sensor
mode after 3 minutes, then
trouble
the outdoor unit restarts.
(TH2)
2. When –40°C or less temp. is
detected again (the second
time) within 30 minutes after
stop of outdoor unit, error
stop is observed with code
Nos. "1111" or displayed.
3. When –40°C or less tem-
perature is detected 30 or
more minutes after stop of
outdoor unit, the stop is re-
garded as the first time and
the process shown in 1. is
observed.
4. 30 minutes after stop of out-
door unit is intermittent fault
check period with LED dis-
played.
Note:
1. Low press. saturation tem-
perature trouble is not de-
tected for 3 minutes after
compressor start, and fin-
ish of defrosting opera-
tions, and during defrost-
ing operations.
2.In the case of short/open of
TH2 sensors before
starting of compressor or
within 10 minutes after
starting of compressor,
"1111" is displayed too.
Cause
1) Gas leak, Gas shortage
2) Insufficient load operations
3) Poor operations of indoor LEV
4) Poor operations of OC controller
LEV1.
Cooling : LEV1
5) Poor operations of ball valve
6) Short cycle of indoor unit
7) Clogging of indoor unit filter
8) Fall in air volume caused by dust
on indoor unit fan
9) Dust on indoor unit heat exchanger
10)Indoor unit block, Motor trouble
5)~10) : Fall in low press. caused
by lowered evaporating capacity in
cooling operation.
11)Short cycle of outdoor unit
12)Dust on outdoor heat exchanger
13)Indoor unit fan block, motor trouble,
and poor operations of fan control-
ler
10)~12) : Fall in low press. caus-
ed by lowered evaporating capa-
city in heating operation.
14)Poor operations of solenoid valve
SV2
Bypass valve (SV2) can not
control low pressure drop.
15)Thermistor trouble (TH2~TH6)
16)Pressure sensor trouble
17)Control circuit board thermistor
trouble and pressure sensor input
circuit trouble
18)Poor mounting of thermistor
(TH2~TH6)
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Checking method & Countermeasure
See Refrigerant amount check.
Check operating conditions and o p -
eration status of outdoor unit.
Check operation status by actually
performing cooling or heating opera-
tions.
Cooling : indoor LEV
LEV1
Heating : indoor LEV
See Trouble check of LEV and so-
lenoid valve.
Confirm that ball valve is fully
opened.
Check indoor unit, and take measu-
res to troube
Check outdoor unit, and take mea-
sures to trouble
Check outdoor unit fan.
See Trouble check of outdoor unit
fan.
See Trouble check of solenoid
valve.
Check resistance of thermistor
See Trouble check of pressure
sensor.
Check inlet temp. and press. of sen-
sor by LED monitor.