Test Run; Before Test Run; Using Remote Controller; Using Sw4 In Outdoor Unit - Mitsubishi Electric MXZ-8B160VA Installationshandbuch

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 supply
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 accumulating
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.
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.

8.2.2. Using SW4 in outdoor unit

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."
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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.
• 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 two to three hours.
(The time necessary to warm up the compressor varies according to atmospheric
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. 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.
SW4-1 ON
Cooling operation
SW4-2 OFF
SW4-1 ON
Heating operation
SW4-2 ON
* After performing the test run, set SW4-1 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 SW4-2 during
the test run. (To change the test run operation mode during the test run, stop
the test run by DIP switch SW4-1. After changing the test run operation mode,
resume the test run by switch SW4-1.)
When a test run is started by "Using SW4 in outdoor unit", even if it carries
out stop instructions by remote controller, outdoor unit does not stop (a test
run is not ended). In this case, please set SW4 in outdoor unit to off.
Note:
Be sure to wait at least 3 minutes after turning on the power supply before set-
ting SW4-1 and SW4-2. If the DIP switches are set before 3 minutes has elapsed,
the test run may not start.