CAMSHAFT AS 20R2152 - Caterpillar

Schraeder Valve
Illustration 9 g01077219
Schraeder valves are used to attach the manifold gauge set to the air conditioning system. Schraeder valves eliminate the need for service valves in the system. The Schraeder valves effectively seal the refrigerant that is inside the system, until the Schraeder valves are opened.The Schraeder fitting on the high side (1) is smaller than the fitting on the low side (2). The difference in the fitting sizes is to prevent connecting the manifold gauge set to the wrong pressure side.Schraeder Valve and Service Hose
Illustration 10 g01077222
Illustration 10 shows a sectional view of a Schraeder valve. Illustration 10 shows a service hose with a Schraeder core depressor. As the high and/or low side pressure hose is threaded onto the Schraeder valve service port, the Schraeder core depressor in the hose depresses the pin in the center of the Schraeder valve. The valve is opened. This allows the refrigerant to flow between the manifold gauge set and the compressor. When the hose is removed, the valve closes automatically.Manifold Gauge Set
Illustration 11 g01077223
Illustration 11 shows a sectional view of the manifold gauge set that is used in a performance test.The compound gauge is connected through the low side internal passage to the low side service connector. The low side service connector is connected through a hose (not shown) to the low pressure side of the air conditioning system. When the low side hand valve is closed, the compound gauge shows only the low side pressure reading.The high pressure gauge is connected through the high side internal passage to the high side service connector. The high side service connector is connected through a hose (not shown) to the high pressure side of the air conditioning system. When the high side hand valve is closed, the high pressure gauge shows only the high side pressure reading.The center internal passages in the manifold connect the center service connector to the low side passages and high side passages. During a performance test, the closed hand valves isolate the low side passages and the high side passages from the center service connector. Adding Refrigerant
Illustration 12 g01077226
Illustration 12 shows a sectional view of the manifold gauge set when you add refrigerant to the system.Opening the low side hand valve opens the center service connector to the low side service connector and the low side gauge. Refrigerant flows into the center service connector, through the manifold gauge, and out through the low side service connector. The compound gauge registers the low side pressure during the operation.Air Conditioning System
Illustration 13 g01077227
With the air conditioner running, carefully check the relative temperatures at the high side and low side of the system. High side temperature should vary from hot at the compressor discharge to warm at the expansion valve. Any sudden drop in temperature indicates a partial blockage at that point.Low side temperature should be cool. There may be large sweating or frosting of the suction line from the evaporator to the accumulator that depends on the ambient temperature.Evaporator Output
Illustration 14 g01077228
With the engine