How To Check Superheat And Subcooling. Negative superheat goes by another name subcooling and the only way a substance can be in the subcooled range is if it is 100% liquid and has given off additional heat below the saturated (mixed) state. While it is true that subcooling is the primary charging measurement on a txv /tev / eev system, subcooling is important to check on every system, every time you connect (whenever possible).
(if the unit has a fixed orifice metering device, use the total superheat charging method.) A low airflow or dirty evaporator can raise subcooling. Once you determine the indoor wet bulb and outdoor dry bulb temperatures, check the manufacturer’s charging chart to determine the proper suction superheat.
Too large an orifice will also lower subcooling (and visa versa).
Subcooling is removing heat from refrigerant below saturation. Air conditioning technician will use measurement of these properties during troubleshooting and maintenance, to gauge performance of an air conditioning system. Negative superheat goes by another name subcooling and the only way a substance can be in the subcooled range is if it is 100% liquid and has given off additional heat below the saturated (mixed) state. Take the high side pressure and convert it to temperature using chart or gauge.