Panasonic U-4LE1E5 Service Manual page 45

7. Compressor
CAUTION
(7) Follow the instructions in "7-3. Dry Core Cleaning" and perform dry core cleaning of the outdoor unit that failed.
7-3. Dry Core Cleaning
If burning or other failures occur repeatedly at compressor, in many cases the cause is acid, sludge, carbon, or
other substances that remain in the refrigeration cycle as the result of insufficient cleaning.
If, when the oil is inspected, there is an outdoor unit where the oil color phase is 4.0 or higher, or where a sharp
odor is present, carry out all steps below to perform dry core cleaning.
* The operating pressure is approximately 1.5 times higher than with R22 or R407C. Therefore use R410A dry
cores.
(1) Refer to "Refrigerant recovery procedures (B): for indoor unit with no ball valve" under "3-2. Refrigerant
Recovery Procedures (Indoor Unit)." Perform pump-down of the refrigerant from all indoor units and inter-unit
tubing to the outdoor unit side.
(2) Cut the liquid tube at all outdoor units where dry cores will be attached, then attach the dry cores and ball
valves as shown in Fig. 2-9.
(3) Operate outdoor unit (in either Heating or Cooling mode).
Fully close the liquid tube valve and ball valve at the outdoor unit where dry cores will be attached.
(4)
(5) Stop operation of outdoor unit.
(6) Connect a refrigerant recovery device to the liquid tube service port (Schrader-type valve) on the outdoor unit
where dry cores will be attached. Recover the refrigerant that is in the tubing. At this time, be careful that air
does not enter the tubing.
CAUTION
(7) As shown in Fig. 2-9, disconnect the tube that runs from the liquid tube valve to the ball valve on the outdoor
unit where dry cores will be attached. Then attach the dry cores.
(8) At all outdoor units where dry cores are attached, pressurize with 3.80 MPa of nitrogen from the liquid tube
service port and check for leaks.
(9) After draining all nitrogen from the tubing, apply vacuum from the liquid tube service port to the outdoor unit
where dry cores are attached until the pressure is –101 kPa {–755 mmHg, 5 Torr} or less.
(10) Fully open the liquid tube valve and ball valve on the outdoor unit where dry cores are attached.
(11) Operate the outdoor unit for approximately 3 hours (in either Heating or Cooling mode).
(12) Follow the above procedure, and replace all dry cores with new dry cores.
(13) Operate all outdoor units for approximately 20 minutes (in either Heating or Cooling mode).
(14) Follow the instructions in "2. Discharging Oil in Compressor" and drain a small amount of the oil from the oil
separators of all outdoor units where dry cores are attached. Check the color phase, odor, and other
characteristics.
(15) If the results show that dry core cleaning is still necessary (for example, a color phase of 4.0 or higher), return
to Step 13 and repeat until the results are normal (including a color phase of 3.5 or less).
CAUTION
(16) Fully close the liquid tube valve and ball valve on the outdoor unit where dry cores are attached.
(17) Connect a refrigerant recovery device to the liquid tube service port (Schrader-type valve) on the outdoor unit
where dry cores are attached. Recover the refrigerant that is in the tubing. At this time, be careful that air does
not enter the tubing.
The connecting port includes a Schrader-type, push-to-release valve.
When disconnecting the hose, pressure will be applied from the refrigerant in
the outdoor unit.
The connecting port includes a Schrader-type, push-to-release valve.
When connecting the hose, internal pressure will be applied from the remaining
refrigerant in the inter-unit tubing. To determine when refrigerant recovery has
been completed, follow the instructions that came with the refrigerant recovery
device.
Perform another dry core replacement after approximately 30 hours of system
operation.
Outdoor Unit Repair Procedures
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Mini VRF SYSTEM
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