Dianetti/Milliman various means as shown in Figure 5. Ice, ice packs, a cooling aerosol (non-CFC, of course) and dry ice are readily available to check valve function. NOTE: Do not use refrigerants like R-134a to cool the power element or refrigerants with a high global warming potential as these are damaging to the environment. It is illegal to vent refrigerants like R-134a to the atmosphere! When cooling is applied to a valve installed on a running system, the low side suction pressure should decrease which indicates the valve is responding and is lowering refrigerant mass flow. If you are holding a non-installed valve in your hand, you should be able to see or feel the operating pin in the valve move. Another check would be to verify that the superheat level is operating at the desired level. Depending upon the system, the operating superheat will run anywhere from roughly 5°F to 15°F. As shown in Figure 6, compare the evaporator outlet temperature and suction pressure. The outlet temperature should closely correspond to temperature / pressure relationship chart. Dianetti/Milliman Figure 6: Compare the evaporator outlet temperature and suction pressure. The outlet temperature should closely correspond to temperature / pressure relationship chart. Dianetti/Milliman Figure 7: These pictures illustrate types of failures due to foreign material inside the system. Figure 8: The right angle TXV is more sensitive to ambient conditions than the block TXV. Failure to wrap the sensing element will have adverse effects on the functionality of this type of valve. October 2020 5 MACS Service Reports