Midea MFA-76CRN1 Technical Manual page 140

Installation of Connective Pipe
5.3 Expelling Air
5.3.1. From the following table, select a method of expelling air.
Table 4:
Length of connective pipe
(single pass)
Less than 5m
5～15m
If the air conditioner is relocated, be sure to use a vacuum pump or refrigerant tank to expel air.
5.3.1.2. Use the refrigerant in the outdoor unit to expel air (see Fig-31 and Fig-32)
Outdoor unit
Stop valve
• Screw up the pipe nuts at A, B, C and D completely.
• Loosen and remove the square-head cover of valves A and B, rotate the square-head spool of valve B
counterclockwise for 45 degrees and stay for about 10 seconds, and then close the spool of valve B tightly.
• Detect leak for all adapters at A, B, C and D. After making sure that no leak exists, open the maintenance
orifice nut of valve A. After all air is expelled, tighten the maintenance orifice nut of valve A.
• Open the spools of valves A and B completely.
• Tighten the square-head cover of valves A and B completely.
5.3.1.3. Use refrigerant tank to expel air (see Fig.6-8 and Fig.6-9)
• Screw up the pipe nuts at A, B, C and D completely.
• Loosen and remove the square-head cover and the maintenance orifice nut of valves A and B.
• Connect the filler hose of the refrigerant tank with the maintenance orifice of valve A.
• Loosen the valve of the refrigerant tank, continue filling refrigerant for 6 seconds to expel the air, and tighten
the nut of valve B quickly.
• Loosen the valve of the refrigerant tank again, and fill the refrigerant for 6 seconds. Detect leak for all
adapters at A, B, C and D. After making sure that no leak exists, screw off the filler hose. After all the filled
refrigerant is expelled, screw up the maintenance orifice nut of valve A quickly.
• Open the square-head spools of valves A and B completely.
• Tighten the square-head cover of valves A and B.
5.3.1.4. Use a vacuum pump to expel the air (Fig-32) (For method of using the manifold valve, see the
operation manual of manifold valve):
140
Use vacuum pump or refrigerant tank.
Air side
A
B
Liquid side
Fig-31
R410A Tropical Split Type Technical Manual
Procedure of expelling air
Use refrigerant in the outdoor unit
Intdoor unit
C
D
pipe adapter
Installation