Mitsubishi SRK10CES, Technical Handbook

Page: 122 / 260

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120
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Operation
mode
Heat exchanger
sensor
Outdoor air
temperature sensor
Discharge pipe
sensor Compressor overload protection is disabled.
(Can be operated.)
(i) Checking the indoor electrical equipment
(i) Indoor unit circuit board check procedure
(ii) Outdoor unit
Phenomenon
Sensor
Shortcircuit Broken wire
Cooling System can be operated normally.
Heating
Defrosting is not performed.
Cooling System can be operated normally.
Heating
Defrosting is not operated.
All modes
System can be operated normally.
Defrosting is performed for 10 minutes at approx. 45 minutes.
System can be operated normally.
Defrosting is performed for 10 minutes at approx. 45 minutes.
Compressor stop
Is there voltage between terminal
blocks
1
and
2
? (AC 220V)
Indoor electrical components
are normal.
Is the voltage between terminal
blocks
2 and 3 oscillating between
DC 0 and 12V?
Inspect power source
for outdoor unit.
Replace fuse.
Replace printed
circuit board.
Is the fuse burnt out? (3.15 A)
YES
YES
YES
NO
NO
NO
(ii) Indoor unit fan motor check procedure
This is a diagnostic procedure for determining if the indoor unit’s fan motor or the circuit board is broken down.
1) Indoor unit printed circuit board output check
a) Turn off the power.
b) Remove the front panel, then disconnect the fan motor lead wire connector.
c) Turn on the power. If the unit operates when the ON/OFF button is pressed, if trouble is detected after the voltages in
the following figure are output for approximately 30 seconds, it means that the circuit board is normal and the fan
motor is broken down.
If the voltages in the following figure are not output at connector pins No. 1 , 4 and 5 , the indoor unit’s circuit
board has failed and the fan motor is normal.
2) DC Fan motor resistance check
Notes (1) Remove the fan motor and measure it without power connected to it.
Notes (2) If the measured value is below the value when the motor is normal, it means
that the fan motor is faulty.
1 2 3 4 5 6
1 2 3 4 5 6
FM
I
DC15V
Indoor unit
circuit board
DC 308V
DC several V
(4~6 V)
CNU
(–)
GND
Blue Y
ello
w
White Blac
k
Red
Measuring Point Resistance when Normal
1 – 3 (Red – Black)
25 M
Ω
or higher
4 – 3 (White – Black) 30 k
Ω
or higher