Mitsubishi Electric City Multi PUMY-P36NHMU Technical & Service Manual page 43

Display
Abnormal point and detecting method
(2) Compressor overcurrent interruption
4250
Abnormal if overcurrent DC bus or
compressor is detected after compressor
starts operating for 30 seconds.
Over current : 27.5A
Outdoor fan motor
4400
Abnormal if rotational frequency of the fan
motor is not detected during DC fan motor
operation.
Fan motor rotational frequency is abnormal if;
• 100 rpm or below detected continuously
for 15 seconds at 20: or more outside
air temperature
• 50 rpm or below or 1500 rpm or more
detected continuously for 1 minute.
Room temperature thermistor (TH21)
5101
When controller detects short (high
temp.)/open (low temp.) in thermistor
during the operation, the operation stops
and the operation changes to protect
mode of restarting in 3minutes. If the
thermistor does not recover in 3minutes,
the operation stops due to detecting
abnormality. In this time, <5101> is
displayed. Then, if the thermistor recover
in 3minutes, it operates normally.
Short: Detected 90
Open: Detected –40
Discharge temperature thermistor (TH4)
When controller detects short/open in
thermistor during the operation, the
outdoor unit stops once and restarts
operation in 3minutes. When the detected
temperature is normal at just before of
restarting, the outdoor unit restarts.
When controller detects short/open in
thermistor at just before of restarting, the
unit stops due to detecting abnormality. In
this time, <5101> is displayed.
For 10 minutes after starting compressor,
for defrosting or for 3minutes after recover
of defrosting, above-mentioned short/open
are not detected.
Short: 216 [421°F] or more (1k )
Open: 0 [32°F] or less (700k )
Note) When outer temperature thermistor
(TH7) is 5 [41°F] or less on cooling,
open detecting is not determined as
abnormality.
Stop valve of outdoor unit is closed.
Decrease of power supply voltage
Looseness, disconnection or converse
of compressor wiring connection
Defective fan of indoor/outdoor units
Short cycle of indoor/outdoor units
Defective input circuit of outdoor
controller board
Defective compressor
Failure in the operation of the DC fan motor
Failure in the outdoor circuit controller board
[194°F] or more
[-40°F] or less
Causes
Connector (CN20) contact failure
Thermistor wiring disconnection or
half disconnection
Thermistor failure
Detecting circuit failure in the
indoor controller board
Connector (TH4) contact failure
Thermistor wiring disconnection or
half disconnection
Thermistor failure
Multi controller board input circuit
failure
43
Check points
Open stop valve.
Check facility of power supply.
Correct the wiring (U·V·W phase) to
compressor.
(Outdoor power circuit board)
Check indoor/outdoor fan.
Solve short cycle.
Replace outdoor controller circuit board.
Check compressor
Before the replacement of the outdoor
controller circuit board, disconnect the
wiring to compressor from the outdoor
power circuit board and check the output
voltage among phases, U, V, W, during
test run (SW7-1 ON). No defect on board
if voltage among phases (U-V, V-W and
W-U) is same. Make sure to perform the
voltage check with same performing
frequency.
Check or replace the DC fan motor.
Check the voltage of the outdoor circuit
controller board during operation.
Replace the outdoor circuit contrlooer
board. (when the failure is still indicated
even after performing the remedy 1
above.)
Check whether the connector
(CN20) in the indoor controller board
is connected or not.
Check whether the thermistor wiring
is disconnected or not.
Check the resistance of thermistor;
0 [32°F]····· 15k
10 [50°F]····· 9.6k
20 [68°F]····· 6.3k
30 [86°F]····· 4.3k
40 [104°F]··· 3.0k
When there is no problem in above
mentioned , replace the indoor
controller board.
Check whether the connector (TH4)
in the multi controller board is
connected or not.
Check whether the thermistor wiring
is disconnected or not.
Check the resistance of thermistor;
When the resistance is not below
value, replace the thermistor.
0 [32°F]····· about 700k
10 [50°F]····· about 410k
20 [68°F]····· about 250k
30 [86°F]····· about 160k
40 [104°F]··· about 104k
1 2 3 4 5 6 7 8
on
Set the SW1 to
When the temperature in multi
controller board is not an actual
temperature, replace the multi
controller board.
1.3: Open
219.4: Short