Mitsubishi SRK90CL-BN Technical Manual page 39

Heat exchanger
Cooling
sensor
Ourdoor air
Cooling
temperature sensor
Discharge pipe
All modes
sensor
(8) Checking the indoor electrical equipment
(a) Indoor PCB check procedure
Is there voltage between terminal
blocks ① and ② ? (AC 220-240V)
YES
Is the fuse burnt out? (3.15 A)
YES
Is the voltage between terminal
blocks ② and ③ oscillating between
DC 0 and 20V?
YES
Indoor electrical components
are normal.
(b) Indoor unit fan motor check procedure
1) Indoor PCB output check
DC several V
(4~6 V)
CNU
2) Fan motor resistance check
Measuring point
① − ③
−
④ − ③
NO
Inspect power source
for outdoor unit.
NO
Replace fuse.
NO
Replace indoor PCB.
(–)
GND
DC15V
⑥ ⑤ ④ ③
⑥ ⑤ ④ ③
FM
I
Resistance when normal
−
k
DC 308~336V
Indoor PCB
② ①
② ①
38
- -
'12 • SRK-T-122
① ④ ⑤
Measuring Resistance when
point normal
① − ③
④ − ③
⑤ − ③
⑥ − ③