Caution Of The Pressure By Check Joint; Pump Down Refrigerant - Hitachi RASC-4HNPE Service Manual

3 Piping work and refrigerant charge
Refrigerant charge
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C A U T I O N
Check for refrigerant leakage thoroughly. In case that a large amount of refrigerant is leaked, it may cause difficulty to breathe or the
emission of harmful gases if fire is lit up in the room. An excess or a shortage of refrigerant is the main cause of trouble with the units.

3.4.3 Caution of the pressure by check joint

When the pressure is measured, use the check joint of gas stop valve (A), and use the check joint of liquid piping (B) in
the figure below.
At that time, connect the pressure gauge according to the following table because of high pressure side and low pressure
side changes by operation mode.
Check joint for gas stop valve "A"
Check joint for piping "B"
Check joint for liquid stop valve "C"
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N O T E
Be careful that refrigerant and oil do not splash to the electrical parts at removing the charge hoses.

3.4.4 Pump down refrigerant

When the refrigerant has to be collected into the RASC unit due to indoor/RASC unit relocation, collect the refrigerant as
follows:
1 Attach the manifold gauge to the gas and the liquid stop valves.
2 Turn ON the RASC unit power source.
3 Set the DSW1-1 pin of the RASC unit PCB at the "ON" side for pump down operation (test run cooling). Close the
liquid stop valve to retain all the refrigerant inside the RASC unit.
4 When the pressure at lower pressure side (gas stop valve) indicates -0.01 MPa (-100 mmHg), perform the following
procedures immediately.
a. Close the gas stop valve.
b. Set the RASC unit DSW1-1 pin at the "OFF" side (To stop the unit operation).
5 Turn OFF the RASC unit power source.
!
C A U T I O N
• Be careful that refrigerant and oil do not splash to the electrical parts at removing the charge hoses.
• Measure the low pressure by the pressure gauge and keep it in a measurement higher than -0.01 MPa. If the pressure is lower than
-0.01 MPa, the compressor may be faulty.
51 SMGB0091 rev.2 - 11/2015
Cooling Operation
Low pressure
High pressure
Exclusive for vacuum pump and refrigerant charge
Right side
B C A
Heating Operation
High pressure
Low pressure
3