1-761 1-12. LEAK TEST, EVACUATION AND ADDITIONAL REFRIGERANT CHARGEPerform an air-tightness test for this package A/C. Check that there is no leakage from any of the connections.Air and moisture in the refrigerant system may have undesirable effects as indicated below.pressure in the system risesoperating current risescooling (or heating) efficiency dropsmoisture in the refrigerant circuit may freeze and blockcapillary tubingwater may lead to corrosion of parts in the refrigerant systemTherefore, the indoor unit and tubing between the indoorand outdoor unit must be leak tested and evacuatedto remove any noncondensables and moisture from thesystem. (Figs. 1- 62 and 1- 63)Air Purging with a Vacuum Pump (for Test Run)PreparationCheck that each tube (both liquid and gas tubes) between theindoor and outdoor units has been properly connected and allwiring for the test run has been completed. Remove the valvecaps from both the gas and liquid service valves on the outdoorunit. Note that both liquid and gas tube service valves on theoutdoor unit are kept closed at this stage. (Fig. 1- 64)Fig. 1- 62 Fig. 1- 63Manifold gauge Vacuum pumpOutletInletLo HiFig. 1- 64Manifold valvePressuregaugeCylindervalve Nitrogen gas cylinder(In vertical standingposition)Charge hoseOpenCloseGas tubeLiquid tubeOutdoor unitCloseThe refrigerant charge at the time of shipment is onlyguaranteed sufficient for a tubing length of up to 30 m.The tubing may exceed this length, up to the maximumpermitted length; however, an additional charge isnecessary for the amount that the tubing exceeds 30 m.(No additional refrigerating machine oil is needed.)1. Leak Test(1) With the service valves on the outdoor unit closed, remove the 7.94 mm flare nut and its bonnet on the gastube service valve. (Save for reuse.)(2) Attach a manifold valve (with pressure gauges) and dry nitrogen gas cylinder to this service port with chargehoses.Use a manifold valve for air purging. If it is not available, use a stop valve for thispurpose. The “Hi” knob of the manifold valve must always be kept closed.(3) Pressurize the system up to 4.15 MPa {42 kgf/cm2 G} with dry nitrogen gas and close the cylinder valvewhen the gauge reading reaches 4.15 MPa {42 kgf/cm2 G}. Then, test for leaks with liquid soap.To avoid nitrogen entering the refrigerant system in a liquid state, the top of thecylinder must be higher than the bottom when you pressurize the system.Usually, the cylinder is used in a vertical standing position.(4) Do a leak test of all joints of the tubing (both indoor and outdoor) and both gas and liquid service valves.Bubbles indicate a leak. Wipe off the soap with a clean cloth after a leak test.(5) After the system is found to be free of leaks, relieve the nitrogen pressure by loosening the charge hoseconnector at the nitrogen cylinder. When the system pressure is reduced to normal, disconnect the hosefrom the cylinder.CAUTIONCAUTION