Panasonic WU-144MF1U9E Installation Instructions - Page 36

6. AIR PURGING Air and moisture in the refrigerant system may have undesirable effects as indicated below. ● pressure in the system rises ● operating current rises ● cooling (or heating) efficiency drops ● moisture in the refrigerant circuit may freeze and block capillary tubing ● water may lead to corrosion of parts in the refrigerant system Therefore, the indoor unit and tubing between the indoor and outdoor unit must be leak tested and evacuated to remove any noncondensables and moisture from the system. ■ Air Purging with a Vacuum Pump (for Test Run) Preparation Check that each tube between the indoor and outdoor units have been properly connected and all wiring for the test run has been completed. Remove the valve caps from all service ports on the outdoor unit. (Fig. 6-2) Note that all service valves on the outdoor unit are kept closed at this stage. The balance tube leak test is not necessary if only 1 outdoor unit is installed. Leak test (1) Attach a manifold valve (with pressure gauges) and dry nitrogen gas cylinder to all service ports with charge hoses. The balance tube leak test is not necessary if only 1 outdoor unit is installed. CAUTION Use a manifold valve for air purging. If it is not available, use a stop valve for this purpose. The "Hi" knob of the manifold valve must always be kept closed. (2) Pressurize the system to no more than 512 psig (36 kgf/cm2G) with dry nitrogen gas and close the cylinder valve when the gauge reading reaches 512 psig (36 kgf/cm2G). Then, test for leaks with liquid soap. To avoid nitrogen entering the CAUTION refrigerant system in a liquid state, the top of the cylinder must be higher than the bottom when you pressurize the system. Usually, the cylinder is used in a vertical standing position. 36 Manifold gauge Vacuum pump Outlet Inlet Fig. 6-1a Valve cap Fig. 6-1b Flare nut Service port cap Fig. 6-2 Manifold valve Pressure gauge Lo Hi Charge hose Cylinder valve Nitrogen gas cylinder (In vertical standing position) Suction tube Discharge tube Liquid tube Balance tube Open Close Open Outdoor unit Close Open Close Open Close Fig. 6-3 88":@&$0J@6JOEC