After subcooling is adjusted and the equipment's operating conditions stabilize, overheating must be checked. Superheating is calculated as the difference between the refrigerant temperature at the evaporator outlet (suction temperature) and the temperature corresponding to the suction pressure (saturated evaporation temperature). To measure the suction temperature, use a bulb or electronic thermometer with a temperature sensor, fixing it to the upper part (precaution against false readings) of the evaporator outlet piping, as close as possible to the bulb of the vacuum valve. expansion isolating it to avoid contact with the environment. Installing a low pressure gauge on the compressor suction, read the pressure and obtain the corresponding saturated temperature in a pressure versus temperature table for R-22 / R-407c.
Suction line temperature - Converted suction pressure = Overheating
If this value is between 6ºC and 8ºC, the expansion valve adjustment is correct. If the value is less than 6ºC, the valve must be closed. If it is above 8ºC it must be opened.
