The most common diagnosis with expansion valves is failed closed or restricted, resulting in underfeeding of the evaporator. The symptoms are low suction, normal subcooling, and high superheat when a TXV fails “shut,” but there are some other issues to watch for that can actually result in overfeeding the coil. Schrader in the Port The […]

The piston (fixed orifice) and TXV (thermostatic expansion valve) are the two most common metering devices in use today, with some modern systems utilizing an electronically-controlled metering device called an EEV (electronic expansion valve). It should be noted that there are other types of fixed orifice metering devices like capillary tubes, but their use is […]

Does setting a thermostat too low cause an air conditioning system set in cool mode to freeze? The answer is no, at least not directly. However, low evaporator load (low return temperature or low airflow) and low outdoor ambient temperature can lead to evaporator coil freezing. Low indoor setpoint can lead to low return air […]