Carrier 69NT40-511-1 Operating And Service Manual

Also see for 69NT40-511-1: Operation and service

Contents

SECTION 66-5 T-268-07d. Evacuate and dehydrate the unit. (Refer to section6.5.)e. Charge unit per section 6.6.6.5 EVACUATION AND DEHYDRATION6.5.1 GeneralMoisture is the deadly enemy of refrigeration systems.The presence of moisture in a refrigeration system canhave many undesirable effects. The most common arecopper plating, acid sludge formation, “freezing-up” ofmetering devices by free water, and formation of acids,resulting in metal corrosion.6.5.2 Preparationa. Evacuate and dehydrate only after pressure leaktest. (Refer to section 6.4.)b. Essential tools to properly evacuate and dehydrateany system include a vacuum pump (8 m3/hr = 5cfm volume displacement, P/N 07-00176-01) andelectronic vacuum gauge.c. If possible, keep the ambient temperature above15.6_C (60_F) to speed evaporation of moisture. Ifthe ambient temperature is lower than 15.6_C(60_F), ice might form before moisture removal iscomplete. Heat lamps or alternate sources of heatmay be used to raise the system temperature.d. Replace the filter-drier with a section of coppertubing with the appropriate fittings. This action willhelp speed the evacuation procedure.6.5.3 Procedurea. Remove all refrigerant using a refrigerant recoverysystem.b. The recommended method to evacuate anddehydrate the system is to connect three evacuationhoses, as shown in Figure 6-4, to the vacuum pumpand refrigeration unit. DO NOT use standardservice hoses, as they are not suited for evacuationpurposes. Also as shown, connect a evacuationmanifold, with evacuation hoses only, to thevacuum pump, electronic vacuum gauge, andrefrigerant recovery system.c. With the unit service valves closed (back seated)and the vacuum pump and electronic vacuum gaugevalves open, start the pump and draw a deepvacuum. Shut off the pump and check to see if thevacuum holds. This operation is to test theevacuation setup for leaks. Repair if necessary.d. Midseat the refrigerant system service valves.e. Open the vacuum pump and electronic vacuumgauge valves, if they are not already open. Start thevacuum pump. Evacuate unit until the electronicvacuum gauge indicates 2000 microns. Close theelectronic vacuum gauge and vacuum pump valves.Shut off the vacuum pump. Wait a few minutes tobe sure the vacuum holds.f. Break the vacuum with clean dry refrigerant gas.Use refrigerant specified for the unit. Raise systempressure to approximately 2 psig, monitoring itwith the compound gauge.g. Remove refrigerant using a refrigerant recoverysystem.h. Repeat steps (e) through (g) one time.i. Remove the copper tubing and change thefilter-drier. Evacuate unit to 500 microns. Close theelectronic vacuum gauge and vacuum pump valves.Shut off the vacuum pump. Wait five minutes to seeif vacuum holds. This procedure checks for residualmoisture and/or leaks.j. With a vacuum still in the unit, the refrigerantcharge may be drawn into the system from arefrigerant container on weight scales. The correctamount of refrigerant may be added by observingthe scales. (Refer to section 6.6)6.6 REFRIGERANT CHARGE6.6.1 Checking the Refrigerant ChargeNOTETo avoid damage to the earth’s ozone layer, usea refrigerant recovery system wheneverremoving refrigerant. When working withrefrigerants you must comply with all localgovernment environmental laws. In the U.S.A.,refer to EPA section 608.NOTESS Set the controller set point to --25_C (--13_F)to ensure that the suction modulation valve isfully open when checking operation of unit.S The refrigerant level should only be checkedwhen the unit is running with the suctionmodulation valve fully open. The containertemperature should be approximately 1.7_C(35_F) or --17.8_C (0_F).a. Connect the gauge manifold to the compressordischarge and suction service valves.