Panasonic U-4LE2E5 Service Manual & Test Run Service Manual page 86

8. Compressor
8-2-2. Dry core cleaning
If burning or other failures occur repeatedly at compressors, 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.
And use the bidirectional dry core for refrigerant R410A.
(A) If a ball valve is installed on the outdoor unit
(1) All units are operated in either Cooling or Heating mode.
For Cooling operation, see the Section 3-2-1. For Heating operation, see the Section 7-1 and 7-2.
(2) If all units are operated in Cooling mode, close the liquid tube service valve then the ball valve.
If all units are operated in Heating mode, close the ball valve then the liquid tube service valve.
* This step is performed in order to expel refrigerant from the tubing between the liquid tube service valve and
the ball valve. Approximately 4 – 5 seconds is a sufficient interval between closing each of the 2 valves.
(3) Press the ON/OFF button on the outdoor unit maintenance remote controller to stop the operation of all units.
* If the outdoor unit maintenance remote controller is not available, use the following method to stop the oper-
ation of all units:
Pull out the SCT connector from the outdoor unit control PCB. When the SCT connector is pulled out, alarm
F12 (sensor trouble) immediately occurs and all outdoor units stop operating. Be sure that you do NOT grasp
the lead wire when pulling out the connector. Removing any other connector may not cause the units to stop.
3 Therefore be sure to pull out only the SCT connector.
(4) Connect a refrigerant recovery device to the liquid tube service port (Schrader-type valve) of outdoor unit
where dry cores will be attached, then recover the refrigerant from the tubing. Be sure that no air enters the
tubing at this time.
CAUTION
(5) As shown in Fig. 11, disconnect the tube that runs from the liquid tube valve to the ball valve on outdoor unit
where dry cores will be attached. Then attach the dry cores.
(6) At outdoor unit where dry cores are attached, pressurize with 3.8 MPa of nitrogen from the liquid tube service
port and check for leaks.
(7) After evacuating all nitrogen gas from the tubing, apply vacuum from the liquid tube service port to outdoor
unit where dry cores are attached until the pressure is –101kPa {–755 mm Hg, 5 Torr} or less.
(8) Fully open the liquid tube valve and ball valve on all outdoor units where dry cores are attached.
(9) Operate all units for approximately 3 hours (in either Heating or Cooling mode).
(10) Follow the above procedure, and replace dry cores with new dry cores.
(11) Operate all units for approximately 20 minutes (in either Heating or Cooling mode).
(12) Follow the instructions in "2. Discharging Compressor Oil" and drain a small amount of the oil from the oil separators
of outdoor unit where dry cores are attached. Check the color phase, odor, and other characteristics.
(13) If the results show that dry core cleaning is still necessary (for example, a color phase of 4.0 or higher)*, return
to Step 11 and repeat until the results return to normal (including a color phase of 3.5 or less)*.
* Color sample sheet for degree of stain
CAUTION
(14) Perform steps (1) – (4), and remove all dry cores. Then connect the tubing between the liquid tube valves and
the ball valves.
(15) At outdoor unit where dry cores were removed, pressurize with 3.8 MPa of nitrogen from the liquid tube service port
and check for leaks.
When the hose is connected, internal pressure is applied by the remaining refrigerant
in the inter-unit tubing. The connection port employs a Schrader-type valve. To
determine when refrigerant recovery is complete, follow the instructions in the
instruction manual of the refrigerant recovery device.
Perform another dry core replacement after approximately 30 hours of system operation.
Outdoor Unit Repair Procedures
3 - 20
Mini VRF SYSTEM