Electronic Expansion Valve Check - Daikin D-Series Service Manual

Si12-619A
6.1.3

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. Compare the EV unit and
2. Turn the power off and back on again, and check to see if all the EVs generate latching
3. If any of the EVs does not generate latching noise 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 conductivity is confirmed in the above step 2, mount a good coil (which generated
Note: Please note that the latching sound varies depending on the valve type.
(1) Valve body catches at fully opened or half
opened position.
(Symptom)
Cooling:
Heating:
(Discharge air temperatures are different by
room)
(2) Valve body catches at complete close
position.
(Symptom)
Cooling:
room .
makes pump down.
(The low pressure of the unit becomes vacuum)
Heating:
Insufficient gas due to liquid refrigerant
stagnation inside
the faulty indoor unit
(Only for heat pump model)
(3) Valve does not open fully.
(Symptom)
pump model.)
Service Diagnosis
the connector number.
sound.
connector and check the conductivity using a tester.
Check the conductivity between pins 1, 3 and 6, and between pins 2, 4 and 5. If there is no
conductivity 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 Body Condition (Symptom)
Water leakage at the no-operation unit
Flow noise of refrigerant in the no-operation unit
Operation halt due to icing protection
The unit does not heat
Refrigerant flow rate vary by unit
Peak cut
The only unit having problem does not cool the
When the only faulty unit is in operation, the unit
IT is activated.
Abnormal discharge pipe temperature
The unit does not heat the room.
IT is activated.
Abnormal discharge pipe temperature
The unit does not cool nor heat (only for heat
IT is actuated.
Abnormal discharge pipe temperature
Check Method / Measure
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
outside air temperature?
YES
Replace the EVn of the room.
Reset power supply and conduct cooling
operation unit by unit.
Check the low pressure
Does
the pressure become into
vacuum zone?
YES
Replace the EVn of the room
Check the number of rotation of shaft if it is 5 and
half from full open to complete close using
manual coil for electronic expansion valve. When
the number of rotation of shaft is less than the
above value, the valve may catch anywhere of
the body.
Check
NO
(R1431)
NO
(R1432)
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