Midea MFA-12HRN1 General Information Manual page 49

MCAC-UTSM-2009-03
How to expel the air with a vacuum pump
Stop valve operation introduction
1. Opening stop valve
1) Remove the cap and turn the valve counter clock-wise with the hexagon wrench.
2) Turn it until the shaft stops. Do not apply excessive force to the stop valve. Doing so may break the
valve body, as the valve is not a backseat type. Always use the special tool.
3) Make sure to tighten the cap securely.
2. Closing stop valve
1) Remove the cap and turn the valve clockwise with the hexagon wrench.
2) Securely tighten the valve until the shaft contacts the main body seal.
Make sure to tighten the cap securely.
For the tightening torque, refer to the table below.
Stop Valve size
φ6.4
φ9.5
φ12.7
φ15.9
φ22.2
φ25.4
Caution:
Always use a charge hose for service port connection.
After tightening the cap, check that no refrigerant leaks are present
Using the vacuum pump
1) Loosen and remove the maintenance nuts of stop valves A and B, and connect the charge hose of the
manifold valve to the service port of stop valve A. (Be sure that stop valves A and B are both closed)
2) Connect the joint of the charge hose with the vacuum pump.
3) Open the Lo-lever of the manifold value completely.
4) Turn on the vacuum pump. At the beginning of pumping, loosen the maintenance nut of stop valve B a
little to check whether the air comes in (the sound of the pump changes, and the indicator of compound
meter turns below zero). Then fasten the maintenance nut.
5) When the pumping has finished, close the Lo-lever of the manifold valve completely and turn off the
vacuum pump. Make pumping for 15 minutes or more and check that the compound meter indicates
5
-76cmHg (-1×10 Pa)
6) Loosen and remove the cap of stop valves A and B to open stop valve A and B completely, then fasten
the cap.
7) Disassemble the charge hose from the service port of stop valve A, and fasten the nut.
Installation
Tightening torque N.M (Turn clockwise to close)
Shaft (valve body)
5.4~6.6
Hexagonal
wrench 4 mm
8.1~9.9
Hexagonal
13.5~16.5
wrench 6mm
Hexagonal
27~33
wrench 10 mm
Installation of the Connecting Pipe
Cap (Valve lid)
13.5~16.5
18~22
23~27
36~44
Maintenance nut
11.5 ～ 13.9
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