Power Supply Waveform Check; Electronic Expansion Valve Check - Daikin MKS-T Series Service Manual

SiSG121917E
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).
[Fig.1]
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
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
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
Note
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.
Part 6 Service Diagnosis
the connector number.
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.
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.
Valve
Possible problem
opening
position
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
Open
[Fig.2]
(R1736)
Reset power supply and conduct cooling operation unit
by unit.
Check the liquid pipe temperature
of no-operation unit.
Almost the same
as the outdoor
temperature?
YES
Check
(R1444)
Check method
NO
The EV is not
defective.
Replace the EV
of the room.
(R16019)
172