Mitsubishi Electric MXZ-8B48NA Installation Manual page 14

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 MQ.
> Do not carry out this test on the control wiring (low voltage circuit) termi-
nals.
AN Warning:
Do not use the air conditioner if the insulation resistance is less than 1 MQ.
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 MQ 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 MQ, the compressor is faulty or the resis-
tance 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.
* The insulation resistance drops due to accumulation of refrigerant in the compres-
sor. The resistance will rise above 1 MQ after the compressor is warmed up for 2
to 3 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 MQ, the compressor is not faulty.
AX 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 weil.
* 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. 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 com-
pressor 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."
14
SWw4-1 ON . .
Sw4.2 OFF Cooling operation
SWw4-1 ON : .
Sw4.2 ON Heating operation
* 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 dur-
ing 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 car-
ries 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
Cin
Note:
Be sure to wait at least 3 minutes after turning on the power supply before
setting SW4-1 and SW4-2. If the DIP switches are set before 3 minutes has
elapsed, the test run may not start.