Mitsubishi Electric CITY MULTI PUHY-400YMF-B Service Handbook page 162

Checking code Meaning, detecting method
1 If saturation temperature sen-
1111 Low
pressure sor TH2 or liquid level sensors
saturation TH3, TH4 detect a tempera-
tempera- ture of – 40°C or less (1st de-
ture tection), the outdoor unit is
sensor temporarily stopped and it en-
abnor- ters the re-start prohibit mode
mality for 3 minutes after which it is
(TH2) started.
(Variable
2 If – 40°C or more is detected
capacity
unit) again within 30 minutes of the
stopping of the outdoor unit,
(2nd detection), the outdoor
unit is temporarily stopped
1112 Liquid again and it enters the re-start
level prohibit mode for 3 minutes
sensing after which it is started.
tempera-
ture 3 If – 40°C or more is detected
sensor again within 30 minutes of the
abnor- outdoor unit being stopped
mality (3rd detection), an error stop
(TH4) is performed and either "1111",
(Outdoor "1112" or "1113" is displayed.
unit)
4 If – 40°C or more is detected
after 30 minutes has passed
since the outdoor unit was
stopped, it is treated as the first
detection and 1 above is re-
peated.
5 The unit is in an error stop de-
lay period for 30 minutes after
1113 Liquid the outdoor unit has been
level stopped, during which time the
detection error stop delay LED is dis-
tempera- played.
ture
sensor Note)
abnor- 1: Low Pressure Saturation
mality Temperature error is not de-
(TH3) tected for 3 minutes after the
(Outdoor start of compressor opera-
unit) tion, during defrosting and
for 3 minutes after recover-
ing from defrosting.
2: "1111", "1112", or "1113" are
also displayed if TH2 ~ TH4
sensors are shorted or open
within 10 minutes before or
after the compressor starts
operating.
Cause
1) Gas leak, insufficient gas.
2) Light load operation.
3) Defective operation of indoor opera-
tion LEV.
4) Defective operation of outdoor opera-
tion LEV1 → Cooling
5) Defective operation of solenoid valve
SV5b → Heating.
Defective operation of 4-way switch-
ing valve 21S4b → Heating.
6) Defective operation of ball valve.
7) Short cycle of indoor unit.
8) Plugged filter of indoor unit.
9) Reduced fan flow due to dirty fan.
10)Dirty indoor heat exchanger.
11)Defective indoor fan block, motor,
Note: For 7) to 11) there is a drop in
low pressure due to a drop in evapo-
ration performance during cooling.
12)Short cycle of outdoor unit.
13)Dirty heat exchanger of outdoor unit.
14)Defective indoor fan block, motor,
defective fan microcomputer opera-
tion, defective operation of solenoid
contactor 52F.
Note: For12) to 14) there is a drop in
low pressure due to a drop in evapo-
ration performance during heating.
15)Defective operation of solenoid
valve SV22/32.
(Full load operation during unload.)
All but model PUHY-400YMF-B.
16)Defective operation of solenoid
valve contactor52C2.
No. 2 compressor operating when
it should be stopped
17)Defective operation of solenoid
valve SV4.
Cannot control low pressure drop
with bypass valve (SV4)
18)Defective thermistor. (TH2 ~ TH6)
19)Defective pressure sensor.
20)Defective input circuit for thermistor
and pressure sensor on main circuit
board.
21)Defective mounting of thermistor
(TH2 ~ TH6).
–159–
Checking method & Countermeasure
Refer to Refrigerant amount check.
Check operating conditions and sta-
tus of indoor unit and outdoor unit.
Perform actual operation of cooling
and heating and check operating sta-
tus. (Check operation of LEV)
Cooling - indoor unit LEV, LEV1
Heating - indoor unit LEV
SV5b (whether or not it is closed)
21S4b (whether or not it is closed)
Refer to Trouble check of LEV and
solenoid valve.
Check if ball valve is fully open.
Inspect indoor unit and repair neces-
sary areas.
Inspect indoor unit and repair neces-
sary areas.
Inspect outdoor unit fan.
Refer to Trouble check of outdoor
unit fan.
Refer to Trouble check of solenoid
valve.
Check resistance of thermistor.
Refer to Toruble check of pressure
sensor.
Check whether or not sensor pick-up
heat and pressue using the LED moni-
tor. Also check if the connector con-
nections are good.