Mitsubishi Electric MXZ-8C48NAHZ Mode D'emploi page 16

8. Test run
8.1. 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 sup-
ply or control wiring, wrong polarity, and no disconnection of one phase
in the supply.
► Use a 500-volt M-ohm tester 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 air conditioner 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.
8.2. Test run
8.2.1. Using remote controller
Refer to the indoor unit installation manual.
• Be sure to perform the test run for each indoor unit. Make sure each indoor
unit operates properly following the installation manual attached to the unit.
• If you perform the test run for all indoor units at once, you cannot detect any
erroneous connection, if any, of the refrigerant pipes and the connecting
wires.
* The compressor operation is not available for 3 minutes at least after the
power is supplied.
• The compressor can emit noise just after turn on the power supply or in case
of low outside air temperature.
About the restart protective mechanism
Once the compressor stops, the restart preventive device operates so the compressor
will not operate for 3 minutes to protect the air conditioner.
8.3. Refrigerant collecting (Pump down)
Perform the following procedures to collect the refrigerant when moving the
indoor unit or the outdoor unit.
1 Turn off the circuit breaker.
2 Connect the low pressure side of the gauge manifold to the service port of the
gas side stop valve.
3 Close the liquid stop valve.
4 Supply power (circuit breaker).
* 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 Confirm that SW3-2 is set to OFF, and then set SW3-1 to ON to perform the
test run for cooling operation. The compressor (outdoor unit) and ventilators
(indoor and outdoor units) start operating and test run for cooling operation
begins. Immediately after performing the test run for cooling operation, set the
outdoor service switch SW2-4 (pump down switch) from OFF to ON.
* Do not continue to operate for a long time with the switch SW2-4 set to ON.
Make sure to switch it to OFF after pump down is completed.
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• The insulation resistance drops due to accumulation of refrigerant in the
compressor. The resistance will rise above 1 MΩ after the compressor is
warmed up for four 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 connec-
tion 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. LED 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.
8.2.2. Using SW3 in outdoor unit
Note:
In case of the test run from outdoor unit, all indoor units operate. Therefore,
you can not detect any erroneous connection of refrigerant pipes and the
connecting wires. If it aims at detection of any erroneous connection, be sure
to carry out the test run from remote controller with reference to "8.2.1 Using
remote controller".
SW3-1 ON
Cooling operation
SW3-2 OFF
SW3-1 ON
Heating operation
SW3-2 ON
* After performing the test run, set SW3-1 to OFF.
• A few seconds after the compressor starts, a clanging noise may be heard from
the inside of the outdoor unit. The noise is coming from the check valve due to
the small difference in pressure in the pipes. The unit is not faulty.
The test run operation mode cannot be changed by DIP switch SW3-2 during
the test run. (To change the test run operation mode during the test run, stop
the test run by DIP switch SW3-1. After changing the test run operation mode,
resume the test run by switch SW3-1.)
6 Fully close the gas stop valve when the pressure reading on the gauge drops
7.1 - 0.0 PSIG (approximately 0.5 - 0.0 kgf/cm
7 Set SW3-1 to OFF to stop the air conditioner operation. (Set the outdoor ser-
vice switch SW2-4 from ON to OFF.)
8 Turn off the power supply (circuit breaker).
* If too much refrigerant has been added to the air conditioner system, the
pressure may not drop to 7.1 PSIG (0.5 kgf/cm
ant collecting device to collect all of the refrigerant in the system, and then
recharge the system with the correct amount of refrigerant after the indoor and
outdoor units have been relocated.
Warning:
When pumping down the refrigerant, stop the compressor before discon-
necting the refrigerant pipes. The compressor may burst and cause injury if
any foreign substance, such as air, enters the system.
2 )
2 ). If this occurs, use a refriger-