Midea MSH-18HRIN1, Installation Manual

12

Air purging

When relocate  the  unit to  another  place, perform evacuation using vacuum pump.

 Make sure the refrigerant added into the air conditioner is liquid form in any case.
 (Not applicable to the units with R22 refrigerant)

Open the valve stem until it hits against the stopper. Do not try to open it further.
Securely tighten the valve stem cap with a spanner or the like.
Valve stem cap tightening torque (See Tightening torque table in previous page ).

Outdoor
unit

Indoor
unit

Refrigerant 

Flare nut

Stopper

Cap

Valve body

Packed valve

Half union

Gas side

Liquid side

A

C

D

B

Valve stem

Fig.22

Fig.23

When Using the Vacuum Pump

(For method  of using a  manifold valve, refer to its operation manual.)
1. Completely tighten the flare nuts, A, B, C, D, connect the manifold valve charge
     hose to  a charge port of the low-pressure valve on the gas pipe side.
2. Connect the charge hose connection to the  vacuum pump.
3. Fully open the handle Lo of the manifold valve.
4. Operate the vacuum pump to evacuate. After starting evacuation, slightly loose the
     flare  nut of the Lo valve on the gas pipe side and check that the air is entering
     (Operation  noise of  the vacuum  pump changes  and  a  compound meter indicates
      0 instead of  minus)
5. After  the  evacuation is complete, fully close the 
    handle Lo of the manifold valve and  stop the 
    operation of the vacuum pump.
    Make evacuation  for  15  minutes or more and 
    check that the compound meter indicates
    -76cmHg  (-1x10 Pa).

o

6. Turn the stem of the packed valve B about 45  
    counterclockwise for 6~7 seconds after the gas 
    coming out, then tighten the flare nut again. Make 
    sure the pressure display in the pressure indicator 
    is a little higher than the atmosphere pressure.
7. Remove the charge hose from the Low pressure charge hose.
8. Fully open the packed valve stems B and A.
9. Securely tighten the cap of the packed valve.

Manifold valve

Compound meter

-76cmHg

Handle Lo

Handle Hi

Charge hose

Charge hose

Vacuum pump

Pressure gauge

Low pressure valve

Fig.24

Caution in handling the packed valve

5