Si12-714
Check
Service Diagnosis
217
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. Compare the EV unit and
the connector number.
2. Turn the power off and back on again, and check to see if all the EVs generate latching
sound.
3. If any of the EVs does not generate latching noise in the above step 2, disconnect that
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.
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
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.
Note:
Please note that the latching sound varies depending on the valve type.
Valve Body Condition (Symptom)
Check Method / Measure
(1) Valve body catches at fully opened or half
opened position.
(Symptom)
Cooling:
Water leakage at the no-operation unit
Flow noise of refrigerant in the no-operation unit
Operation halt due to icing protection
Heating:
The unit does not heat
Refrigerant flow rate vary by unit
(Discharge air temperatures are different by
room)
Peak cut
Reset power supply and conduct cooling
operation unit by unit.
(2) Valve body catches at complete close
position.
(Symptom)
Cooling:
The only unit having problem does not cool the
room .
When the only faulty unit is in operation, the unit
makes pump down.
(The low pressure of the unit becomes vacuum)
IT is activated.
Abnormal discharge pipe temperature
Heating:
Insufficient gas due to liquid refrigerant
stagnation inside
the faulty indoor unit
(Only for heat pump model)
The unit does not heat the room.
IT is activated.
Abnormal discharge pipe temperature
Reset power supply and conduct cooling
operation unit by unit.
(3) Valve does not open fully.
(Symptom)
The unit does not cool nor heat (only for heat
pump model.)
IT is actuated.
Abnormal discharge pipe temperature
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 the liquid pipe temperature
of no-operation unit.
YES
Is it
almost same as the
outside air temperature?
(R1431)
NO
Replace the EVn of the room.
Check the low pressure
Does
the pressure become into
vacuum zone?
(R1432)
Replace the EVn of the room
YES
NO
