Mitsubishi Electric PUHZ-ZRP35VKA Service Manual page 28

10-1. REFRIGERANT COLLECTING (PUMP DOWN)
When relocating or disposing of the indoor/outdoor unit, pump down the system following the procedure below so that no refriger-
ant is released into the atmosphere.
1 Turn off the power supply (circuit breaker).
2 Connect the low-pressure valve on the gauge manifold to the charge plug (lowpressure side) on the outdoor unit.
3 Close the liquid stop valve completely.
4 Supply power (circuit breaker).
* When power is supplied, make sure that "CENTRALLY CONTROLLED" is not displayed on the remote controller. If "CEN-
TRALLY CONTROLLED" is displayed, the refrigerant collecting (pump down) cannot be completed normally.
* Start-up of the indoor-outdoor communication takes about 3 minutes after the power (circuit breaker) is turned on. Start the
pump-down operation 3 to 4 minutes after the power (circuit breaker) is turned on.
5 Perform the refrigerant collecting operation (cooling test run).
* Push the pump-down SWP switch (push-button type) on the control board of the outdoor unit. The compressor and ventilators
(indoor and outdoor units) start operating (refrigerant collecting operation begins). (LED1 and LED2 on the control board of
the outdoor unit are lit.)
* Only push the pump-down SWP switch if the unit is stopped. However, even if the unit is stopped and the pump-down SWP
switch is pushed less than 3 minutes after the compressor stops, the refrigerant collecting operation cannot be performed.
Wait until the compressor has been stopped for 3 minutes and then push the pump-down SWP switch again.
6 Fully close the ball valve on the gas pipe side of the outdoor unit when the pressure gauge on the gauge manifold shows 0.05
to 0 MPa [Gauge] (approx. 0.5 to 0 kgf/cm²) and quickly stop the air conditioner.
* Because the unit automatically stops in about 3 minutes when the refrigerant collecting operation is completed (LED1 off,
LED2 lit), be sure to quickly close the gas ball valve. However, if LED1 is lit, LED2 is off, and the unit is stopped, open the
liquid stop valve completely, close the valve completely after 3 minutes or more have passed, and then repeat step 5. (Open
the gas ball valve completely.)
* If the refrigerant collecting operation has been completed normally (LED1 off, LED2 lit), the unit will remain stopped until the
power supply is turned off.
* Note that when the extension piping is very long with a large refrigerant amount, it may not be possible to perform a pump-
down operation. In this case, use refrigerant recovery equipment to collect all of the refrigerant in the system.
7 Turn off the power supply (circuit breaker), remove the gauge manifold, and then disconnect the refrigerant pipes.
Warning:
When pumping down the refrigerant, stop the compressor before disconnecting the refrigerant pipes.
• If the refrigerant pipes are disconnected while the compressor is operating and the stop valve (ball valve) is open, the
pressure in the refrigeration cycle could become extremely high if air is drawn in, causing the pipes to burst, personal
injury, etc.
10-2. START AND FINISH OF TEST RUN
• Operation from the indoor unit
Execute the test run using the installation manual for the indoor unit.
• Operation from the outdoor unit
By using the DIP switch SW4 on the control board of outdoor unit, test run can be started and finished, and its operation
mode (cooling/heating) can be set up.
1 Set the operation mode (cooling/heating) using SW4-2.
2 Turn on SW4-1 to start test run with the operation mode set by SW4-2.
3 Turn off SW4-1 to finish the test run.
• There may be a faint knocking sound around the machine room after power is supplied, but this is
no problem with product because the linear expansion pipe is just moving to adjust opening pulse.
• There may be a knocking sound around the machine room for several seconds after compressor
starts operating, but this is no problem with product because the check valve itself, generates the
sound because pressure difference is small in the refrigerant circuit.
Note:
The operation mode cannot be changed by SW4-2 during test run. (To change test run mode, stop the unit by SW4-1,
change the operation mode and restart the test run by SW4-1.)
OCH527B
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<SW4>
ON
OFF
1 2
Stop Operation
Cooling Heating