Pumping Out Refrigerant From Outdoor Unit - Panasonic U-4LE1E5 Service Manual

6. Pumping Out Refrigerant from Outdoor Unit

Required equipment and tools: Jumper wire with clips, adjustable wrench, set of manifold gauge valves, vacuum
This procedure is used to move refrigerant of the faulty outdoor unit (except compressor) into indoor units, and
refrigerant tubing.
(1) Connect the manifold gauge valves at the Lo-side to the low-pressure sensor outlet of the outdoor unit to be
repaired. Also connect the refrigerant recovery cylinder to any one of the normal outdoor units at the liquid line
service port (Schrader type, with push-to-release valve). Perform the connection work quickly so that no air is
allowed to enter.
* Connecting the refrigerant recovery cylinder is done to prevent pressure from rising excessively during the
backup operation by recovering the refrigerant from the outdoor unit to be repaired.
2
(Measure the weight of the refrigerant and cylinder itself beforehand and provide sufficient safety measures,
such as installing a high-pressure cutout in the circuit.)
CAUTION
(2) Short-circuit the TEST pin (CN-TEST) on the outdoor control PCB of the main unit.
(3) After operating the unit for a while, judge whether it is running in Cooling or Heating mode by touching the gas
line cautiously with your fingers. If it is running in Cooling mode, follow the instructions given in (4) through (6).
* The gas line reaches a low temperature (under 20°C) during cooling operation, and a high temperature (over
60°C) during heating operation.
CAUTION
(4) If the unit is in Cooling mode, temporarily release the short-circuit across the test run pins on the outdoor
control PCB of the unit. Then, short-circuit the STOP pin (CN-STOP) to stop operation of the unit.
(5) Short-circuit the MODE pin (CN-MODE) on the outdoor control PCB of the main unit.
* The 4-way valve will not change at this moment; rather, it changes just before start of operation. (It is difficult
to confirm the change by listening for the sound.)
(6) Short-circuit the TEST pin (CN-TEST) on the outdoor control PCB of the unit. Let the unit operate for a while, then
check if it is in Heating mode by cautiously touching the gas line.
(7) Slowly close the liquid line service valve of the outdoor unit to be repaired.
(8) When the low-pressure gauge reading shows 0.5 MPa or less, pull out the EXL2 connector (3P) (YEL)
(CN-RC) on the control PCB of the outdoor unit to be repaired and then fully close the gas line service valve
immediately.
* By pulling out the EXL2 connector, all outdoor units stop immediately.
CAUTION
(9) Connect the high-pressure sensor outlet of the outdoor unit to be repaired to the manifold gauge valves at the
Hi-side. Also connect the manifold gauge valves to the refrigerant recovery unit. Perform the connection work
quickly so that no air is allowed to enter.
(10) Open both Hi- and Lo-side valves on the manifold gauge valves, and recover the refrigerant remaining in the
outdoor unit. After that, measure the amount of recovered refrigerant.
pump, refrigerant recovery unit, pre-purged refrigerant cylinder for recovery, and
hex wrench (4 mm for liquid tube and 5 mm for gas tube).
The hoses may be subject to internal pressure from the refrigerant inside the
outdoor unit. Check that the manifold gauge valves are fully closed beforehand.
A Schrader-type, push-to-release valve is provided at each connection port.
Be careful when testing the temperature of the gas line with your fingers, because
the tubing becomes very hot (about 60°C) when Heating mode is used.
While closing the valve, the outdoor unit may suddenly stop. This is because a
protective function, such as for discharge temperature, is working. In this case
also, fully close the gas line service valve immediately.
Outdoor Unit Repair Procedures
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Mini VRF SYSTEM