Test Run; Special Functions - Mitsubishi Electric PUHZ-SW AA Series Instruction Manual

9. Test run

9.1. Before test run
► After completing installation and the wiring and piping of the indoor and
outdoor units, check for refrigerant leakage, looseness in the power supply
or control wiring, wrong polarity, and no disconnection of one phase in the
supply.
► Use a 500-volt megohmmeter to check that the resistance between the
power supply terminals and ground is at least 1 MΩ.
► Do not carry out this test on the control wiring (low voltage circuit) termi-
nals.
Warning:
Do not use the outdoor unit if the insulation resistance
is less than 1 MΩ.
Insulation resistance
After installation or after the power source to the unit has been cut for an extended
period, the insulation resistance will drop below 1 MΩ due to refrigerant accumulat-
ing in the compressor. This is not a malfunction. Perform the following procedures.
1. Remove the wires from the compressor and measure the insulation resistance of
the compressor.
2. If the insulation resistance is below 1 MΩ, the compressor is faulty or the resist-
ance dropped due the accumulation of refrigerant in the compressor.
3. After connecting the wires to the compressor, the compressor will start to warm
up after power is supplied. After supplying power for the times indicated below,
measure the insulation resistance again.
9.2. Using remote controller
Refer to the indoor unit installation manual.
Note :
Occasionally, vapor that is made by the defrost operation may seem as if smoke come up from the outdoor unit.

10. Special Functions

10.1. Refrigerant collecting (pump down)
Perform the following procedures to collect the refrigerant when moving the indoor
unit or the outdoor unit.
1 Supply power (circuit breaker).
* When power is supplied, make sure that "CENTRALLY CONTROLLED" is not
displayed on the remote controller. If "CENTRALLY CONTROLLED" is dis-
played, 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.
* In the case of multi-units control, before powering on, disconnect the wiring
between the master indoor unit and the slave indoor unit. For more details
refer to the installation manual for the indoor unit.
2 After the liquid stop valve is closed, set the SWP switch on the control board of
the outdoor unit to ON. The compressor (outdoor unit) and ventilators (indoor and
outdoor units) start operating and refrigerant collecting operation begins. LED1
and LED2 on the control board of the outdoor unit are lit.
* Only set the SWP switch (push-button type) to ON if the unit is stopped. How-
ever, even if the unit is stopped and the SWP switch is set to ON less than 3
minutes after the compressor stops, the refrigerant collecting operation cannot
be performed. Wait until compressor has been stopped for 3 minutes and then
set the SWP switch to ON again.
• The insulation resistance drops due to accumulation of refrigerant in the com-
pressor. The resistance will rise above 1 MΩ after the compressor is warmed
up for 4 hours.
(The time necessary to warm up the compressor varies according to atmos-
pheric conditions and refrigerant accumulation.)
• To operate the compressor with refrigerant accumulated in the compressor,
the compressor must be warmed up at least 12 hours to prevent breakdown.
4. If the insulation resistance rises above 1 MΩ, the compressor is not faulty.
Caution:
• The compressor will not operate unless the power
supply phase connection is correct.
• Turn on the power at least 12 hours before starting
operation.
- Starting operation immediately after turning on the main power switch can result
in severe damage to internal parts. Keep the power switch turned on during the
operational season.
► The followings must be checked as well.
• The outdoor unit is not faulty. LED1 and LED2 on the control board of the outdoor
unit flash when the outdoor unit is faulty.
• Both the gas and liquid stop valves are completely open.
3 Because the unit automatically stops in about 2 to 3 minutes when the refrigerant
collecting operation is completed (LED1 off, LED2 lit), be sure to quickly close
the gas stop valve. If LED1 is lit and LED2 is off and the outdoor unit is stopped,
refrigerant collection is not properly performed. Open the liquid stop valve com-
pletely, and then repeat step 2 after 3 minutes have passed.
* 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.
4 Turn off the power supply (circuit breaker).
* Note that when the extension piping is very long with large refrigerant amount,
it may not be possible to perform a pump-down operation. When performing
the pump-down operation, make sure that the low pressure is lowered to near
0 MPa (gauge).
Warning:
• When pumping down the refrigerant, stop the com-
pressor before disconnecting the refrigerant pipes.
The compressor may burst if air etc. get into it.
• Do not perform pump down work when there is a
gas leak. The intake of air or other gases causes
abnormally high pressure in the refrigeration cycle,
which may cause explosion or injury.
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