Daikin SUPER MULTI NX G Series Service Manual page 159

SiUS12-928_A
6.1.2 Electronic Expansion Valve Check
Check No.04
Conduct the followings to check the electronic expansion valve (EV).
1. Check to see 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 to see if all the EVs generate latching sound.
3. If any of the EVs does not generate latching sound in the above step 2, disconnect that
4. If no EV generates latching sound in the above step 2, the outdoor unit PCB is faulty.
5. If the continuity is confirmed in the above step 3, mount a good coil (which generated latching
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.
Valve opening
Service Diagnosis
the connector number.
connector and check the continuity using a tester.
Check the continuity between the pins 1 - 6 and 3 - 6, and between the pins 2 - 5 and 4 - 5. If
there is no continuity between the pins, the EV coil is faulty.
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.
Possible problem
position
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 halt due to anti-icing
function
Heating:
 Flowing noise of refrigerant in the
unit which is not in operation
 The unit does not heat the room.
Close Cooling:
 The problem unit does not cool
the room.
 Only the problem unit is in
operation, the unit starts pump
down.
(The low pressure of the unit
becomes vacuum.)
 Abnormal discharge pipe
temperature
Heating:
 Refrigerant shortage due to
stagnation of liquid refrigerant
inside the faulty indoor unit
 The unit does not heat the room.
 Abnormal discharge pipe
temperature
Check method
Reset power supply and conduct cooling operation
unit by unit.
Check the liquid pipe temperature
of no-operation unit.
Is it almost
same as the outdoor
temperature?
YES
Reset power supply and conduct cooling operation
unit by unit.
Check the low pressure
Does the
pressure become into
vacuum zone?
YES
Check
NO
The EV is not
defective.
Replace the EV
of the room.
(R11266)
NO
The EV is not
defective.
Replace the EV
of the room.
(R11267)
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