1. Run the condensing unit until pressures and temperatures stabilize.
2. Read and record the liquid pressure at the liquid line pressure port fitting at the condensing unit
3. Place a digital temperature probe against the liquid line near the liquid gauge pressure port. Read and record the temperature.
4. Reference the face of your high pressure gauge or use a Temperature/Pressure chart and convert the measured liquid pressure to the corresponding condenser coil saturation temperature for the refrigerant being used. Record this value.
5. Next, subtract the measured liquid line temperature from saturation temperature. The result is your actual liquid subcooling level.