Carrier 69NT40-561-300, Operation And Service Manual

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7–7 T-365
7.7 REFRIGERANT CHARGE
WARNING
!
EXPLOSION HAZARD Failure to follow this WARNING can result in death, serious personal
injury and / or property damage.
Never use air or gases containing oxygen (O2) for leak testing or operating the product.
Charge only with R-134a: Refrigerant must conform to AHRI Standard 700 specification.
7.7.1 Checking the Refrigerant Charge
NOTICE
Use a refrigerant recovery system whenever removing refrigerant. When working with refriger-
ants you must comply with all local government environmental laws. In the U.S.A., refer to EPA
Section 608.
1. Connect the gauge manifold to the compressor discharge and suction service valves. For units operating on
a water cooled condenser, change over to air cooled operation.
2. Bring the container temperature to approximately 0°C (32°F) or below. Then set the controller set point to -
25°C (-13°F).
3. Partially block the condenser coil inlet air. If covering the lower portion of the coil is not sufficient, remove
the left hand infill panel and cover the left side of the coil. Increase the area blocked until the compressor dis-
charge pressure is raised to approximately 12.8 bar (185 psig).
4. On units equipped with a receiver, the level should be between the glasses. On units equipped with a water-
cooled condenser, the level should be at the center of the glass. If the refrigerant level is not correct, con-
tinue with the following paragraphs to add or remove refrigerant as required.
7.7.2 Adding Refrigerant to System (Full Charge)
1. Evacuate unit and leave in deep vacuum. (Refer to Section 7.6 .)
2. 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.
3. Open liquid valve on cylinder. Open liquid line valve half-way and allow 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.
NOTICE
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.
4. Backseat manual liquid line valve (to close off gauge port). Close liquid valve on cylinder.
5. Start unit in cooling mode. Run for approximately 10 minutes and check the refrigerant charge.
7.7.3 Adding Refrigerant to System (Partial Charge)
1. Examine refrigerant system for any evidence of leaks, repair as necessary. (Refer to Section 7.5 .).
2. Maintain the conditions outlined in Section 7.7.1 .
3. Fully backseat the suction service valve and remove the service port cap.
4. Connect charging line between suction service valve port and cylinder of refrigerant R-134a. Open VAPOR
valve.
5. 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.