Daikin Emura RXJ20A5V1B Service Manual page 85

To perform an operation check of the expansion valve
RXJ20~50A + FTXJ-A(W)(S)(B)
Split Emura 3 R32
ESIE22-04B – 2022.08
Prerequisite: First perform an electrical check of the expansion valve, see
"4.4.1 Checking procedures" [
1 Turn ON the power of the unit.
INFORMATION
When power is switched ON, PCB checks all expansion valve coil windings by current
check. If winding is short or open, expansion valve error is triggered.
2 Start the unit operation via the user interface.
3 With the unit operating, connect the service monitoring tool to the unit.
4 When the expansion valve is closed according to the service monitoring tool,
check the inlet and outlet of the valve with a contact thermometer or use an
expansion valve stethoscope to see if refrigerant flows through the expansion
valve. Check that the valve is NOT bleeding.
Result: There MUST be NO flow through the expansion valve.
5 When the expansion valve is open according to the service monitoring tool,
check the inlet and outlet of the valve with a contact thermometer or use an
expansion valve stethoscope to see if refrigerant flows through the expansion
valve.
Result: Refrigerant MUST flow through the expansion valve.
6 Wait for the PCB to command the expansion valve to open (when closed) or to
close (when open) (pulse output to expansion valve visible on service
monitoring tool).
INFORMATION
If the PCB does NOT command the expansion valve to open or close (when it is
supposed to), perform a check of the appropriate thermistors and pressure sensors
(as their measurements control the operation of the expansion valve(s)).
7 While in opening or closing sequence each expansion valve winding (Ф1, 2, 3,
4) is supplied with 12 V DC from the PCB. You will need a good multimeter,
where its range is set to about 20 V DC, and during opening or closing
sequence you may be able to measure the supply voltage for a short time. If
you set the multimeter range to Auto, then most likely you may NOT read a
value between switching ranges. The best way to check is to feel the
movement of the valve by touching, rather than trying to measure the driving
voltage.
8 When the expansion valve was commanded to close, check the inlet and
outlet of the valve with a contact thermometer or use an expansion valve
stethoscope to see if refrigerant flows through the expansion valve. Check
that the valve is NOT bleeding.
Result: There MUST be NO flow through the expansion valve.
9 When the expansion valve was commanded to open, check the inlet and
outlet of the valve with a contact thermometer or use an expansion valve
stethoscope to see if refrigerant flows through the expansion valve.
Result: Refrigerant MUST flow through the expansion valve.
4
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Service manual
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