SiSG121917E
Check
Part 6 Service Diagnosis
172
Note
8.4 Power Supply Waveform Check
Check No.11
Measure the power supply waveform between No. 1 and No. 2 on the terminal strip, and check
the waveform disturbance.
Check if the power supply waveform is a sine wave (Fig.1).
Check if there is waveform disturbance near the zero-cross (sections circled in Fig.2).
8.5 Electronic Expansion Valve Check
Check No.12
Conduct the followings to check the electronic expansion valve (EV).
1. Check if the EV connector is correctly inserted in the PCB. Match the EV unit number and
the connector number.
2. Turn the power OFF and ON again, and check if all the EVs generate latching sound.
3. If any of the EVs does not generate latching sound in the step 2 above, disconnect that
connector and check the continuity using a multimeter.
Check the continuity between the pins 1 - 6, 3 - 6, 2 - 5, 4 - 5 (between the pins 1 - 5, 2 - 5, 3
- 5, 4 - 5 for the harness 5P connectors). If there is no continuity between the pins, the EV
coil is faulty.
4. If no EV generates latching sound in the step 2 above, the outdoor unit PCB is faulty.
5. If the continuity is confirmed in the step 3 above, mount a good coil (which generated
latching sound) in the EV unit that did not generate latching sound, and check to see if that
EV generates latching sound.
If latching sound is generated, the outdoor unit PCB is faulty.
If latching sound is not generated, the EV unit is faulty.
Please note that the latching sound varies depending on the valve type.
If the system keeps operating with a defective electronic expansion valve, the following problem
may occur.
[Fig.1]
[Fig.2]
(R1736)
(R1444)
Valve
opening
position
Possible problem
Check method
Open
Cooling:
Flowing noise of refrigerant in the
unit which is not in operation
Water leakage at the unit which is
not in operation
Operation half due to anti-icing
function
Reset power supply and conduct cooling operation unit
by unit.
Check the li
qu
id pipe temperat
u
re
of no-operation
u
nit.
YES
(R16019)
N
O
The EV is not
defecti
v
e.
Replace the EV
of the room.
Almost the same
as the o
u
tdoor
temperat
u
re?
