To verify that the refrigerant charge is correct, it is necessary to measure the subcooling of the system before adjusting the superheat with the equipment operating in stabilized conditions. Subcooling is the difference between the saturation temperature corresponding to the discharge pressure (saturated condensation temperature) and the temperature of the liquid line. To measure the temperature in the liquid line, use a bulb or electronic thermometer with a temperature sensor, fixing it in the pipeline as close to the condenser outlet (before the dryer filter) and isolating it to avoid contact with the environment. Installing a discharge pressure gauge at the compressor discharge, read the pressure and obtain the corresponding saturated temperature in a pressure table versus refrigerant gas temperature R-22 / R407c.
Converted discharge pressure - Liquid line temperature = Subcooling
The subcooling value must be between 6ºC and 10ºC. If the value is below 6ºC it will be necessary to add refrigerant, and if it is above 10ºC remove the refrigerant. Measure the subcooling again.
