8) Phenomenon Observed After Shortcircuit, Wire Breakage On Sensor - Mitsubishi Heavy Industries SRR25ZM-S Technical Manual

(8) Phenomenon observed after shortcircuit, wire breakage on sensor

(a) Indoor unit
Operation
Sensor
mode
Cooling
Room temperature
sensor
Heating
Cooling
Heat exchanger
sensor
Heating
(b) Outdoor unit
Operation
Sensor
mode
(b) Outdoor unit
Cooling
Heat exchanger
■ Humidity sensor operation
Operation
sensor
Heating
Sensor
mode
Failure mode
Cooling
Cooling
Heat exchanger
Ourdoor air
①
sensor
temperature sensor Heating
②
Heating
Cooling
Ourdoor air
①②
Discharge pipe
temperature sensor
Heating
All modes
① ②
sensor
Discharge pipe
All modes
sensor
(9) Checking the indoor electrical equipment
(9) Checking the indoor electrical equipment
(a) Indoor PCB check procedure
(a) Indoor PCB check procedure
Is there voltage between terminal
blocks ① and ② ? (AC 220/230/240
Is there voltage between terminal
V)
blocks ① and ② ? (AC 220/230/240
V)
YES
YES
Is the fuse burnt out? (3.15 A)
Is the fuse burnt out? (3.15 A)
YES
NO
Is the voltage between terminal
blocks ② and ③ oscillating between
Is the voltage between terminal
DC 0 and 20V?
blocks ② and ③ oscillating between
DC 0 and 20V?
YES
YES
Indoor electrical components
are normal.
Indoor electrical components
are normal.
(b) Indoor unit fan motor check procedure
(b) Indoor unit fan motor check procedure
1) Indoor PCB output check
1) Indoor PCB output check
DC several V
(4~6 V)
DC several V
(4-6 V)
CNU
CNU
Shortcircuit
Freezing cycle system protection trips and stops the compressor.
Shortcircuit
Compressor stop.
Shortcircuit
The compressor cannot pick up its speed owing to the current Control input circuit resding
safe so that the designed capacity is not achieved.
The compressor cannot pick up its speed owing to the heating
overload protection so that the designed capacity is not achieved.
NO
Inspect power source
for outdoor unit.
NO
Inspect power source
for outdoor unit.
NO
Replace fuse.
YES
Replace fuse.
NO
Replace indoor PCB.
NO
Replace indoor PCB.
(–)
GND
(–)
DC15V
GND
DC15V
⑥ ⑤ ④ ③
⑥ ⑤ ④ ③
⑥ ⑤ ④ ③
⑥ ⑤ ④ ③
FM
I
Phenomenon
Phenomenon
Phenomenon
Defrosting is performed for 10 minutes at approx. 35 minutes.
Air conditioning system operation
Defrosting is performed for 10 minutes at approx. 35 minutes.
Defrosting is performed for 10 minutes at approx. 35 minutes.
Defrosting is performed for 10 minutes at approx. 35 minutes.
DC 308~336V
DC 308-336V
Indoor PCB
② ①
Indoor PCB
② ①
② ①
② ①

- -
'15 • SR-T-185
Disconnected wire
'09•SRK-DB-087D
'09•SRK-DB-087D
Disconnected wire
Disconnected wire
.
① ④ ⑤
① ④ ⑤
Measuring Resistance when
point normal
Measuring Voltage range when
① − ③
point normal
④ − ③
① − ③
−
⑤ − ③
④ − ③
⑥ − ③
⑤ − ③
−