nents. Tiny grains of debris can enter the underside of the power element and become trapped between the diaphragm and the lower housing. This will result in an eventual failure as the diaphragm can crack causing the power element to lose its refrigerant charge. See Figure 7. Proper mounting of the thermal sensing bulb to the evaporator outlet is essential for proper superheat control when using right angle brass TXVs. Figure 8 illustrates securely attaching and wrapping the bulb in thermal insulating tape. Attachment can be achieved by a clip as shown or a tighly fitting clamp (a worm gear clamp would be a good example). Dianetti/Milliman It is also important to note that when servicing a mobile air conditioning system to follow proper flushing procedures when replacing system compo- Dianetti/Milliman Figure 11: Right angle TXV with a filter screen in the inlet port to prevent debris from entering the valve. When servicing systems using right angle brass TXVs, it is important to make sure the thermal sensing bulb is mounted properly. The valve may overfeed refrigerant to the evaporator causing a loss of performance and possible damage to the compressor. Thoroughly clean the thermal bulb and mounting surfaces prior to attaching them. Intimate contact as shown in Figure 9 between the thermal bulb and the evaporator outlet tube is critical for proper superheat control. Another area which is critical to proper superheat control with right angle brass TXVs is bulb mounting location. On 5/8" diameter or larger suction lines, mount the thermal bulb at the 4 o'clock position. On smaller suction lines, mount the thermal bulb near the top of the line (Figure 10). Figure 12: Plugged right angle TXV. October 2020 7 MACS Service Reports