Subcooling is measured to adjust the refrigerant charge on AC/Heat Pump Systems with a TXV expansion device.
- Run the condensing unit until pressures and temperatures stabilize.
- Read and record the liquid pressure at the liquid line pressure port fitting at the condensing unit.
- Place a digital temperature probe against the liquid line near the liquid gauge pressure port. Read and record the temperature.
- Reference the face of your high pressure gauge or use a pressure / temperature chart and convert the measured liquid pressure to the coresponding condenser coil saturation temperature for the refrigerant being used. Record this value.
- Next, subtract the measured liquid line temperature from the saturation temperature. The result is your actual liquid subcooling level.
- Refrigerant: R-22
- Liquid pressure: 200 PSIG
- Corresponding condenser saturation temperature: 100F
- Liquid line temperature: 90F
- 100F – 90F =Liquid subcooling
- Liquid subcooling = 10F