7–7 T-359
Adding Refrigerant to System (Full Charge)
a. Evacuate unit and leave in deep vacuum. (Refer to Section 7.3.4.)
b. Place cylinder of R-134a on scale and connect charging line from cylinder to liquid line valve. Purge
charging line at liquid line valve and then note weight of cylinder and refrigerant.
c. Open liquid valve on cylinder. Open liquid line valve half-way and allow the liquid refrigerant to flow into the
unit until the correct weight of refrigerant (refer to Section 3.2) has been added as indicated by scales.
It may be necessary to finish charging unit through suction service valve in gas form, due to pressure
rise in high side of the system.
d. Backseat manual liquid line valve (to close off gauge port). Close liquid valve on cylinder.
e. Start unit in cooling mode. Run for approximately 10 minutes and check the refrigerant charge.
Adding Refrigerant to System (Partial Charge)
a. Examine the unit refrigerant system for any evidence of leaks. Repair as necessary. (Refer to Section
7.3.3).
b. Maintain the conditions outlined in paragraph Section 7.3.5.
c. Fully backseat the suction service valve and remove the service port cap.
d. Connect charging line between suction service valve port and cylinder of refrigerant R-134a. Open VAPOR
valve.
e. Partially frontseat (turn clockwise) the suction service valve and slowly add charge until the refrigerant
appears at the proper level. Be careful not to frontseat the suction valve fully, if the compressor is operated
in a vacuum, internal damage may result.
7.4 COMPRESSOR
Make sure power to the unit is OFF and power plug disconnected before replacing the com-
pressor.
Before disassembly of the compressor, be sure to relieve the internal pressure very carefully
by slightly loosening the couplings to break the seal.
The scroll compressor achieves low suction pressure very quickly. Do not use the compressor
to evacuate the system below 0 psig. Never operate the compressor with the suction or dis-
charge service valves closed (frontseated). Internal damage will result from operating the com-
pressor in a deep vacuum.
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