SiUS28-902_B
Check
Service Diagnosis
149
Check for Fan Motor Connector
(1) Turn the power supply off.
(2) With the fan motor connector disconnected, measure the resistance between each pin, then
make sure that the resistance is more than the value mentioned in the following table.
Check for Power Transistor
Judgement is made through cable check with an analog tester.
(1) Do not touch the energized part (high voltage part) for at least 10 minutes after the power is
turned OFF.
(2) Be sure to touch the ground terminal with a hand to release static electricity from the body
(to prevent PCB from being damaged).
(3) With a tester, take measurements at the following spots and confirm that residual electric
charge of the power transistor is DC 50V or less.
(4) After checking the residual electric charge, remove the connector of the outdoor unit fan
motor. When the outdoor unit fan is rotated by strong headwind, remove the connector of the
outdoor unit fan motor after confirming that the outdoor unit fan has stopped because
electrical energy is stored in the capacitor and there may be a risk of electric shock.
(5) Remove the wire connecting the power transistor and the compressor. Remove it from the
compressor terminal side.
During this work, be careful not to deform Faston terminal at the end of the connecting wire.
(6) Using an analog tester, measure resistance and fill in the blanks in the following table.
In case of unbalanced resistance for one of the 3 phases in each table (when the resistance
value is equal to 5 times or more than the other resistance values), the power transistor is
broken.
In normal cases, each phase shows a similar resistance value.
CHECK 3
Measurement point
Judgement
1 - 4
1M
or more
2 - 4
100k
or more
3 - 4
100
or more
4 - 7
100k
or more
GND
1 White
2 Orange
3 Brown
4 Blue
5
6
7 Red
CHECK 4
Tester
Resistance
Tester
Resistance
(+)
(-)
(+)
(-)
C+
U
C-
U
C+
V
C-
V
C+
W
C-
W
U
C+
U
C-
V
C+
V
C-
W
C+
W
C-
Electrical
e
qu
ipment
b
ox
O
u
tdoor
u
nit
fan connector
Front face
Gro
u
nd terminal
Resid
u
al
v
oltage
meas
u
rement spot
U
V
W
C+
C-
Comp.
M1C
Red White Blue
U
V
W
Outdoor Unit
PCB
