Pressure Gauge Readings

The pressure gauge readings shown represent an expansion valve type system using a Nippondenso 10-cylinder compressor. See Fig 1-Fig 9 . Gauge indications will vary depending on system configuration and compressor application.

Temperature and humidity, as well as other factors, affect pressure gauge readings. Compared to R-12 systems, pressure readings on R-134a systems are generally lower for low side pressure and higher for high side pressure. Pressure gauge readings should be used only as a guide.

NOTE: For additional information, see the latest lemon-25® AUTOMOTIVE AIR CONDITIONING BASIC SERVICE & TRAINING MANUAL.

Fig 1: Normally Functioning R-134a A/C System

Fig 2: Some Moisture In R-134a System

Fig 3: Low R-134a Charge

Fig 4: Poor R-134a Refrigerant Circulation

Fig 5: No R-134a Refrigerant Circulation

Fig 6: Insufficient Cooling Of Condenser Or R-134a Refrigerant Overcharge

Fig 7: Air In R-134a System

Fig 8: Expansion Valve Improperly Mounted Or Heat Sensing Tube Defective (Opening Too Wide)

Fig 9: Compressor Malfunction