Compressor Replacement Instructions (Only P500 Type) - Mitsubishi Electric PU(H)Y-P250YGM-A Service Handbook

[ IX Troubleshooting ]

[6] Compressor Replacement Instructions (Only P500 type)

Follow the instructions below when replacing the compressor.
When replacing the compressor No.1 (inverter drive), determine if the compressor is malfunctioning or the inverter is malfunc-
tioning.
When only one compressor is malfunctioning, operate the compressor for approximately an hour in emergency operation mode
before the replacement, check the items below, and replace the compressor after examining whether the return oil circuit is
working properly or not.
Refer to the diagram on the right for the temperature of each section.
<When normal>
1) Temperature of A = Temperature of C,
and Temperature of A > Outdoor temperature + 10deg°C
2) Temperature of B = Temperature of C,
and Temperature of B > Outdoor temperature + 10deg°C
<When abnormal>
When 1) is abnormal (out of range)
Return oil failure due to SV1 circuit failure
-> Replace SV1 circuit.
When 2) is abnormal (out of range)
Return oil failure due to capillary blockage
-> Replace the capillary
1) Check that the main power is OFF.
When replacing the compressor due to megger failure and when the megger is 1M ohm or more, megger drop is
likely due to the liquified refrigerant entering and accumulating in the compressor. Turn the power off after powering
the crankcase heater at least 12 hours, and apply megger again.
2) Remove the fin guard, the front panel and the front partition plate on the right (as you face the front).
3) Collect the refrigerant from the service check joints on both high and low-pressure sides.
When collecting refrigerant from the accumulator, perform proper work with the reference of refrigerant collecting
method from the accumulator.
4) The oil must not be leaked from the drain oil pipe that is located on the oil balance pipe.
Note:
Do not splash oil.Do not leave the refrigerant circuit open for a long time, as the oil rapidly absorbs moisture.
The collected oil cannot be reused.
5) After draining oil from the refrigerant and the drain oil plug, remove the metal fitting-1 or the flare nuts (2 places)
that connect the compressor and the oil balance pipe, and bend the oil balance pipe so as not to apply an excess
force.
6) Close the oil balance pipe attachment point with a cap to prevent the oil from leaking.
7) Remove the compressor terminal cover, and remove the power supply wiring.
8) Remove the discharge temperature thermistor and the sound-proof material that is wrapped around the compres-
sor.
9) Remove the crankcase heater. After replacing the dryer, do not leave the refrigerant circuit for long time.
10) Heat the brazed part of the discharge pipe and the suction pipe, and remove the pipes.
11) Remove the compressor fixing nuts and the metal fitting-2 (3 places on HN71).
12) Replace the compressor with the service compressor.
13) Braze the discharge pipe and the suction pipe.
14) Attach the oil balance pipe to both compressors. Replace the dryer with a new one. After replacing the dryer, do
not leave the refrigerant circuit for long time.
Note:
When replacing the compressor and when the equal oil pipe is damaged or irreparably deformed, after replacing the
compressor, heat the junction of the equal oil pipe, remove the equal oil pipe, and braze the service equal oil pipe.
15) Close the ball valves in the outdoor unit (both on the liquid and the gas side), and pressurize up to 4.15MPa with
nitrogen from the check joints for high and low-pressure service.
16) After confirming the airtightness, release the nitrogen gas.
17) Open the ball valves in the outdoor unit (both on the liquid and the gas side), and perform vacuuming.
18) While vacuuming, add the same amount of oil that is collected from the drain oil plug on the oil balance pipe in
the procedure 4) as necessary.
Note:
The oil to be added must be MEL32 made by Nisseki Mitsubishi.When adding oil, the oil must not absorb moisture,
and do not use the oil that is over a year old.
Do not draw out the oil in the compressor when returning the compressor to find the cause of compressor malfunction.
19) Attach the crankcase heater.
Note: Attach the appropriate crankcase heater to the appropriate compressor.
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Compressor 4-way valve
SV1 A
Oil
B
separator
Capillary
C