Carrier 69NT20-531-300 manual Refrigerant Charge

6.7 REFRIGERANT CHARGE

6.7.1 Checking the Refrigerant Charge

NOTE

To avoid damage to the earth’s ozone layer, use a refrigerant recovery system whenever remov- ing refrigerant. When working with refriger- ants you must comply with all local govern- ment environmental laws. In the U.S.A., refer to EPA section 608.

a. Connect the gauge manifold to the compressor dis- charge and suction service valves. For units operating on a water cooled condenser, change over to air cooled operation.

b. Bring the container temperature to approximately 1.7_C (35_F) or -17.8_C (0_F). Then set the control- ler set point to -25_C (-13_F) to ensure that the suc- tion modulation valve is fully open. (Position of the suction modulating valve may be checked at control- ler function code Cd01.)

c. Partially block the condenser coil inlet air. Increase the area blocked until the compressor discharge pres- sure is raised to approximately 12 kg/cm@ (175 psig).

d.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, contin- ue with the following paragraphs to add or remove re- frigerant as required.

6.7.2 Adding Refrigerant to System (Full Charge)

a. Evacuate unit and leave in deep vacuum. (Refer to paragraph 6.6.)

b.Place cylinder of R-134a on scale and connect charg- ing 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 paragraph 2.2) has been added as indicated by scales.

NOTE

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. (Refer to section paragraph 6.7.3)

d. Backseat manual liquid line valve (to close off gauge port). Close liquid valve on cylinder.

e. Start unit in cooling mode. Run approximately 10 minutes and check the refrigerant charge.

6.7.3Adding Refrigerant to System (Partial Charge)

a.Examine the unit refrigerant system for any evidence of leaks. Repair as necessary. (Refer to paragraph 6.5.)

b.Maintain the conditions outlined in paragraph 6.7.1

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 ser- vice 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.

6.8 COMPRESSOR -- Model RSH105

WARNING

Make sure power to the unit is OFF and power plug disconnected before replacing the compressor.

WARNING

Before disassembly of the compressor make sure to relieve the internal pressure very carefully by slightly loosening the couplings to break the seal.

CAUTION

The scroll compressor achieves low suction pressure very quickly. Do not use the com- pressor to evacuate the system below zero psig. Never operate the compressor with the suction or discharge service valves closed (frontseated). Internal damage will result from operating the compressor in a deep vacuum.

6.8.1 Removal and Replacement of Compressor

NOTE

Service compressor contains a nitrogen charge. Due to the hygroscopic nature of the oil, time the compressor is left open to the atmosphere should be minimized as much as possible.

a.Procure a replacement compressor kit. A list of items contained in the compressor kit is provided in Table 6-1.

b.If the compressor is operational, pump the unit down (refer to paragraph 6.4).

6-5 T-309