Midea LC3 Series Technical & Service Manual page 84

Midea LC3 Series DC Inverter Air conditioner Technical Service Manual
MCAC-UTSM-202006
5.4 Pipe connection
Flaring
Use a pipe cutter to cut off the pipe, and rotate the pipe cutter repeatedly to cut off the pipe.
Insert the pipe into the connection nut flare.
Outer
diameter(mm) Max.
Φ6.4
Φ9.5
Φ12.7
Φ15.9
Φ19.1
5.5 Fasten the nut
Align the connection pipe, tighten the connecting nut with a hand, and tighten them with a wrench as shown in
the figure below.
5.6 Air discharge
Use a vacuum pump to discharge the air.
• Loosen and remove the service port nut of check valve A and connect the manifold valve charging hose to
the service port of check valve A (check valves A and B are closed).
• Connect the charging hose connector to the vacuum pump.
• Fully open the manifold valve Lo (low pressure) handle.
• Start the vacuum pump. When the vacuum is started, slightly loosen the service port nut of the check valve B
to check if the air enters (the vacuum pump noise changes, and the multimeter reading changes from negative
to 0). Tighten the service port nut.
• After the vacuum is complete, fully close the manifold valve low pressure (Lo) handle and stop the vacuum
pump.
Vacuum the pipe for 15 minutes or more, check whether the multimeter reading is -1.0X10Pa (-755mmHg).
• Loosen and remove the square head covers of check valves A and B, fully open the check valves A and B,
and tighten the square head covers of the check valves A and B.
• Remove the charging hose from the service port of check valve A and tighten the nut.
(Refer to its manual for the use of the manifold valve)
A(mm)
Min.
8.7 8.3
12.4 12.0
15.8 15.4
19.0 18.6
23.3 22.9
Outdoor Unit
A
B
Check valve
Liquid side
Gas side
83
Indoor Unit
C
D
Pipe connector