Mitsubishi Electronics R410A Test run, Before test run, Refrigerant collecting Pump down

7. Test run

7.1. Before test run

sAfter 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.

sUse a 500-volt M-ohm tester to check that the resistance between the power supply terminals and ground is at least 1 MΩ.

sDo 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.

•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 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 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 op- erational season.

sThe 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.

7.2. Test run

7.2.1.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 compres- sor will not operate for 3 minutes to protect the air conditioner.

7.2.2.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 con- necting wires. If it aims at detection of any erroneous connection, be sure to carry out the test run from remote controller with reference to “7.2.1 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.)

7.3. Refrigerant collecting (Pump down)

Before removing air conditioners for transfer to another location, always close the stop valve (for both liquid and gas pipes) located at the outdoor unit, then remove the indoor and outdoor units. At this time, the refrigerant in the indoor unit will be dis- charged. To minimize the refrigerant discharged, a pump down operation is required. This operation collects the refrigerant present inside the air conditioner and sends it into the heat exchanger located in the outdoor unit.

Pump down procedure

1Operate all indoor units in cooling mode and check that the operation mode has changed to “COOL”. (Set the units so that cooling operation mode is activated during the pump down operation (when the TEST RUN button is pressed).)

2Connect a gauge manifold valve (with pressure gauge) to the stop valve of the gas pipe, to enable measurement of refrigerant pressure.

3After setting the outdoor service switch SW3-2 to OFF, set the switch SW3-1 to

ON. (The unit will start in cooling mode.)

4After the cooling operation has been carried out for approximately five minutes, set the outdoor service switch SW2-4 (pump down switch) from OFF to ON.

5Close the stop valve on the liquid pipe, with the cooling operation still ON. (Pump down operation will start.)

6When the reading of the pressure gauge reaches 0 to 0.1 MPa [14.5 PSIG] or when approximately 5 minutes have elapsed following the start of the pump down operation, fully close the stop valve on the gas pipe and stop the air conditioner by setting the switch SW3-1 to OFF immediately.

7Set the outdoor service switch SW2-4 from ON to OFF.

8Remove the gauge manifold valve and put the cap back onto each stop valve.

Note:

1Never carry out pump down operation if the amount of refrigerant inside the indoor unit is larger than the amount of charge-less refrigerant. Carrying out a pump down operation when the amount of refrigerant ex- ceeds the amount of charge-less refrigerant will cause an extreme pres-

sure rise and may result in an accident.

2Do 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.

3Test run can be carried out when the test run switch SW3-1 is ON. Switch SW3-2 is used to operating mode selection. (On: Heating, OFF: Cooling)

4Time required for a pump down operation is three to five minutes after the

stop valve on the liquid pipe has been closed. (It depends on the ambient temperature and amount of refrigerant inside the indoor unit.)

5Ensure that the reading of the pressure gauge does not drop below 0 MPa (0 PSIG). If it drops 0 MPa [0 PSIG] (i.e. vacuum is created), air will be drawn into the unit if there are any loose connections.

6Even if the reading of the pressure gauge does not drop below 0 MPa [0 PSIG], always stop the pump down operation within approximately five min- utes after the stop valve on the liquid pipe has been fully closed.

11