Mitsubishi Heavy Industries FDT90VNPWVH Service Manual page 124

blocks ② and ③ oscillating between
DC 0 and 20V?
YES
Indoor electrical components
are normal.
(b) Indoor fan motor check procedure
This is a diagnostic procedure for determining if the indoor fan motor or the indoor unit PCB is broken down.
(i) Indoor unit PCB output check
1)
2)
3)
in the following figure are output for approximately 30 seconds, it means that the indoor unit PCB is normal and
the fan motor is broken down
failed
DC several V
(4-6 V)
CNU
⑥
⑥
(ii) Fan motor resistance check
Measuring point
① − ③
−
④ − ③
−
PCB.
(–)
GND
DC15V
⑤ ④ ③ ②
⑤ ④ ③ ②
FM
i
Resistance when normal
M
k
123
-
① ④
DC 308-336V
Indoor unit PCB
①
①
-
'19 • PAC-SM-334
⑤
the indoor unit PCB has
Measuring Voltage range when
point normal
① − ③ −
④ − ③
⑤ − ③
−