Carrier GR-45 Operation And Service

Contents

Carrier GR-45 Operation And Service Manual pdf 39 page image

T-295 4-66123451. Cylinder Valve and Gauge2. Pressure Regulator3. Nitrogen Cylinder4. Pressure Gauge (0 to 400 psig = 0 to 27.22 bar)5. Bleed-Off Valve6. 1/4 inch ConnectionFigure 4-7. Checking High Pressure Switchc. Connect an ohmmeter across switch terminals.d. Set nitrogen pressure regulator higher than switchcutout setting. (refer to paragraph 1.3.)e. Close cylinder valve and open bleed--off valve. Opencylinder valve and slowly close bleed--off valve. Theswitch should open, (no continuity) with in requiredcut out tolerance.f. Close cylinder valve and release pressure through thebleed-off valve. As pressure drops, switch shouldclose, (continuity) within required cut in tolerance.g. Replace or re--install switch (as required) and recon-nect wiring.4.11 FILTER-DRIER1 2 3 4 5 6231. Filter-Drier InletService Valve2. Valve Service Port3. Flare Nut4. Filter-Drier5 Liquid LineSolenoid Valve6. Filter-Drier OutletService ValveFigure 4-8. Filter--Drier Removal4.11.1 To Check Filter--DrierThe filter--drier (see Figure 4-8) must be changed if thereceiver mounted moisture indicator shows highmoisture content or the drier is partially restricted.Check for a restriction by feeling the inlet and outletlines of the filter--drier. If the outlet side feels cooler thanthe inlet side, then the filter--drier should be changed4.11.2 To Replace Filter--Driera. Perform a low side pump down. Refer to paragraph4.5.1.b. Turn the driver’s A/C switch to “OFF” position.c. Frontseat the filter--drier outlet service valve andplace a new filter-drier near the unit for immediateinstallation.WARNINGTHE FILTER-DRIER MAY CONTAINLIQUID REFRIGERANT. SLOWLYLOOSEN THE FLARE NUTS AND AVOIDCONTACT WITH EXPOSED SKIN OREYES.d. Using two open end wrenches, slowly crack open theflare nuts on each side of the filter-drier. Remove thefilter-drier.e. Remove seal caps from the new filter-drier. Apply alight coat of compressor oil to the flares.f. Assemble the new filter-drier to lines ensuring thatthe arrow on the body of the filter-drier points in thedirection of the refrigerant flow (refrigerant flowsfrom the receiver to the evaporator). Finger tightenflare nuts.g. Tighten filter-drier flare nuts using two open endwrenches.h. Evacuate the filter--drier and lines by connecting avacuum pump as shown in Figure 4-4. Evacuate to500 microns.i. Backseat (fully close) both service valve ports and re-place valve caps.j. Test filter-drier for leaks.k. Check refrigerant level.4.12 CONDENSER COIL REPLACEMENTa. Place the driver’s A/C switch in the OFF position andtag to prevent unintentional starting.b. Remove the refrigerant charge. Refer to paragraph4.5.4.c. Remove the connection access covers to gain accessto the mounting screws. Remove the mountingscrews in the connection compartment and at the rearof the unit next to the receiver supports.d. Remove the filter--drier mounting screws and removethe filter--drier. Disconnect the discharge hose.e. Begin to lift the coil assembly at the left rear. Lift toclear the service valve then push to the right to clearthe precharge valve. Continue to lift towards the frontto clear the sight glasses and remove from the unit.f. To install the coil assembly, reverse the removal pro-cedure.