Measuring refrigerant pressure is fundamental to diagnosing and charging any system. Done correctly, it tells you whether a system is operating properly; done carelessly, it can mislead or even vent refrigerant.
What you need
A quality gauge manifold (or digital gauges) rated for the refrigerant, the correct hoses and fittings, and a reliable temperature clamp for superheat/subcooling. Make sure your equipment is suitable for A2L refrigerants if applicable.
Taking readings
- Connect the low-side gauge to the suction line and the high-side to the liquid line, with the system running and stable
- Read both pressures and convert to saturation temperatures using a P/T chart for that refrigerant
- Measure actual line temperatures to calculate superheat (low side) and subcooling (high side)
Interpreting the results
Compare against the manufacturer’s targets. Low suction pressure with high superheat often indicates undercharge or a restriction; high pressures can mean overcharge, poor condenser airflow or non-condensables.
Minimise refrigerant loss
Use low-loss fittings and purge hoses correctly — venting refrigerant is both wasteful and illegal under F-Gas rules.
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