Checking The Indoor Electrical Equipment - Mitsubishi SRK25ZSP-W Service Manual

Cooling
Heat exchanger
sensor
Heating
Cooling
Ourdoor air
temperature sensor
Heating
Discharge pipe
All modes
sensor

(9) Checking the indoor electrical equipment

(a) Indoor unit PCB check procedure
Is there voltage between terminal
blocks ① and ② ? (AC 220/230/240
V)
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 unit PCB output check
DC several V
(4-6 V)
CNU
⑥
⑥
2) Fan motor resistance check
Measuring point
① − ③
−
④ − ③
−
operation
operation
NO
Inspect power source
for outdoor unit.
NO
Replace fuse.
NO
Replace indoor unit
PCB.
(–)
GND
DC15V
⑤ ④ ③ ②
⑤ ④ ③ ②
FM
i
Resistance when normal
k
32
-
Defrost operation is performed for 10 minutes at approx. 35 (model SRC35:45) minutes.
Defrost operation is performed for 10 minutes at approx. 35 (model SRC35:45) minutes.
① ④
DC 308-336V
Indoor unit PCB
①
①
-
'18 • SRK-SM-259
unit
unit
⑤
unit
Measuring Voltage range when
point normal
① − ③
-
④ − ③
⑤ − ③
-