Carrier 69NT40-561-019 Operation And Service Manual

Contents

T-359 7–6Procedure - Complete SystemNOTERefer to Partial System procedure for information pertaining to partial system evacuation and dehydration.a. Remove all refrigerant using a refrigerant recovery system.b. The recommended method to evacuate and dehydrate the system is to connect evacuation hoses at thecompressor suction and liquid line service valve (see Figure 7.4). Be sure the service hoses are suited forevacuation purposes.c. Test the evacuation setup for leaks by backseating the unit service valves and drawing a deep vacuum withthe vacuum pump and gauge valves open. Shut off the pump and check to see if the vacuum holds. Repairleaks if necessary.d. Midseat the refrigerant system service valves.e. Open the vacuum pump and electronic vacuum gauge valves, if they are not already open. Start the vacuumpump. Evacuate unit until the electronic vacuum gauge indicates 2000 microns. Close the electronic vac-uum gauge and vacuum pump valves. Shut off the vacuum pump. Wait a few minutes to be sure the vac-uum holds.f. Break the vacuum with clean dry refrigerant 134a gas. Raise system pressure to roughly 0.14 bar (2 psig),monitoring it with the compound gauge.g. Remove refrigerant using a refrigerant recovery system.h. Repeat steps e. and f. one time.i. Remove the copper tubing and change the filter drier. Evacuate unit to 500 microns. Close the electronicvacuum gauge and vacuum pump valves. Shut off the vacuum pump. Wait five minutes to see if vacuumholds. This procedure checks for residual moisture and/or leaks.j. With a vacuum still in the unit, the refrigerant charge may be drawn into the system from a refrigerant con-tainer on weight scales.Procedure - Partial Systema. If refrigerant charge has been removed from the low side only, evacuate the low side by connecting theevacuation set-up at the compressor suction valve and the liquid service valve but leave the service valvesfrontseated until evacuation is completed.b. Once evacuation has been completed and the pump has been isolated, fully backseat the service valves toisolate the service connections and then continue with checking and, if required, adding refrigerant in accor-dance with normal procedures.7.3.5 Refrigerant ChargeChecking the Refrigerant ChargeNOTEUse a refrigerant recovery system whenever removing refrigerant. When working with refrigerants youmust comply with all local government environmental laws. In the U.S.A., refer to EPA Section 608.a. Connect the gauge manifold to the compressor discharge and suction service valves.b. Bring the container temperature to approximately 0°C (32°F) or below. Then set the controller set point to-25°C (-13°F).c. Partially block the condenser coil inlet air. Increase the area blocked until the compressor discharge pres-sure is raised to approximately 12.8 bar (185 psig).d. On units equipped with a receiver, the level should be between the glasses. If the refrigerant level is not cor-rect, continue with the following paragraphs to add or remove refrigerant as required.