Mitsubishi Electric PUZ-WZ50VAA Service Manual page 87

OPERATING PROCEDURE
8. Removing the 4-way valve, LEV (LEV-A, LEV-B, LEV-C) and
high pressure switch and pressure sensor
Note:
Be sure to perform the work in compliance with Section 2
"Safety precaution" of this manual and check the following.
• The power-supply breaker of the appliance is turned off.
• There is no refrigerant leak from the unit.
• There is no ignition sources in work area.
• The work area is provided adequate space and ventilation.
(1) Remove the inlet and outlet water pipe. *1 (See Photo 5-1)
(2) Remove the service panel, top panel and cover panel. (See
Photo 1-1)
(3) Recover refrigerant from two refrigerant circuit (INV and
FIXED) in accordance with the following procedure. *2
• Remove the refrigerant
• Purge the circuit with inert gas for 5 min
• Evacuate down the refrigerant circuit to a pressure of 30 kPa
absolute or lower
• Purge again with inert gas for 5 min
(4) Remove the side panel (R). (See Photo 5-1, 5-2)
[Removing the 4-way valve]
(5) Remove the 4-way valve coil. (See Photo 7-1)
(6) Cutting the pipe inside the welded part of 4-way valve (4
positions) to remove the 4-way valve. *3 (See Photo 8-1)
(7) Remove the remaining pipe welded part of 4-way valve (4
positions).
[Removing the LEV]
(5) Remove the LEV coil. (See Photo 7-2, 7-3)
(6) Remove the LEV fixed to the pipe with a band and rubber
mount. (See Photo 7-2, 7-3)
(7) Cutting the pipe inside the welded part of LEV (2 positions)
to remove the LEV. *3 (See Photo 8-3)
(8) Remove the remaining pipes welded part of the LEV. (See
Photo 8-3)
[Removing the high pressure switch]
(5) Disconnect the lead wire from the high pressure switch. (See
Photo 7-1)
(6) Remove the high pressure switch fixed to the pipe with a
band, rubber mount and rubber tube. (See Photo 8-4)
(7) Cutting the pipe inside the welded part of high pressure
switch (1 position) to remove high pressure switch. *3 (See
Photo 8-5)
(8) Remove the remaining pipe welded part of the high pressure
switch. (See Photo 8-5)
[Removing the pressure sensor]
(5) Disconnect the relay connector of pressure sensor. (See
Photo 2-2)
(6) Remove the pressure sensor fixed to the pipe with a band,
rubber mount and rubber tube. (See Photo 8-6)
(7) Cutting the pipe inside the welded part of pressure sensor (1
position) to remove the pressure sensor. *3 (See Photo 8-7)
(8) Remove the remaining pipe welded part of the pressure sen-
sor. (See Photo 8-7)
*1 Drain the water in outdoor unit before removing the
water piping.
*2 Work on the refrigerant circuit with flammable refrigerant
in safety group A3 may only be carried out by authorised
heating contractors. These heating contractors must be
trained in accordance with EN 378 Part 4 or IEC 60335-2-
40 Annex HH.
*3 Be sure to remove parts to be replaced by cutting with
pipe cutter, NOT by flame nor by electric saw, etc.
*4 When installing the following parts, cover it with a wet
cloth to prevent it from heating as the temperature
below, then braze the pipes so that the inside of pipes
are not oxidized:
• 4-way valve; 120°C or more
• LEV; 120°C or more
• High pressure switch; 100°C or more
• Pressure sensor; 100°C or more
OCH816
PHOTOS/FIGURES
Photo 8-1
Inside
Inside
Outside
Outside
Photo 8-2
Bands and rubber mounts
Photo 8-4
Band, rubber mount
and rubber tube
Photo 8-6
Band, rubber mount
and rubber tube
87
4-way valve
Cutting position
Welded part
Photo 8-3
Inside
Cutting position
Outside
Welded part
Inside
Outside
Photo 8-5
Cutting position
Inside
Welded part
Outside
Photo 8-7
Cutting position
Inside
Welded part
Outside