Mitsubishi Electric CITY MULTI PUHY-400YMF-C Service Handbook page 151

(13) Solder the discharge piping, suction piping, volume control valve piping (All but model PUHY-(P)400YMF-C) and
process piping (All but model PUHY-(P)400YMF-C).
(14) Attach the oil equalization pipe to both compressors. In the case of the PUHY-P-YMF-C, replace the dryer with a
new one. After replacing the dryer, do not leave the refrigerant circuit in the open state for a long period of time.
(15) Shut the ball valves (both the fluid side and gas side) on the outdoor unit and apply nitrogen from the high and low
pressure service check joint up to a pressure of A, checking to make sure there is no leakage.
2.94 MPa ------- PUHY-400·500 YMF-C
*A =
2.98 MPa ----- PUHY-P400·500 YMF-C
(16) Discharge the nitrogen gas.
(17) Open the ball valves (both the liquid side and gas side) on the outdoor unit and apply a vacuum.
(18) Install the belt heater.
Caution: Do not mistake the belt heaters for the 2 compressors (particularly the PUHY-400 YMF-C).
(19) Install the pipe fasteners (a) ~ (d) in their original places.
Caution: If these fasteners are not mounted as they were originally, it could cause the pipe to crack during opera-
tion, so install them securely.
(20) Mount the discharge temperature thermistor and attach the insulating cover.
(21) Connect the power cable to the compressor's terminals.
Caution: Be careful not to mistake the three phases. If the wires are connected wrong, it could damage the
compressor.
(22) When applying the vacuum is completed, charge the unit with the amount of refrigerant it was charged with at the
factory, and with the supplementary amount it was charged with when it was installed.
(23) After reconfirming the phase of the power cable wires at the compressors terminals, carry out an insulation
resistance check, then install the terminal cover and turn on the main power supply, checking if current is flowing to
the belt heater.
Caution: When the ambient temperature is 5 C or lower, if you do not spend 4 hours with the power on to the
heater, the unit will not function even when the remote control is operated.
(24) Make sure the liquid side and gas side ball values are opened.
(25) Run all the indoor units and make sure they are operating normally.
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