Performance Chart: Notes

The Nissan A/C system uses a thermal expansion valve to provide a restriction which causes a pressure change and also controls refrigerant flow through the evaporator.

The best way to diagnose a condition in the refrigerant system is to note the system pressures (shown by the manifold gauges) and the clutch cycle rate and times. Then, compare the findings to the charts.

• The system pressures are low (compressor suction) and high (compressor discharge).
• A clutch cycle is the time the clutch is engaged plus the time it is disengaged (time on plus time off).
• Clutch cycle times are the lengths of time (in seconds) that the clutch is ON and OFF.