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  1. How To
  2. Diagrams: System Pressure Chart

Diagrams: System Pressure Chart

Get a quick look at what an average A/C system looks like, along with the compressor manufacturer and what the specific R-134a requirements are for your car.

R-134a TEMPERATURE PRESSURE CHART
(Tabla de Temperaturas y Lecturas)
Ambient
Temperature °F / °C
(Temperatura Ambiental)		 Low-Pressure Gauge
(Puerto de Servicio del Lado
de Baja Presion)		 High-Pressure Gauge
(Puerto de Servicio del Lado
de Lado de Alta Presion)
65°F (18°C) 25-35 psi / 172-241 kPa 135-155 psi / 931-1069 kPa
70°F (21°C) 35-40 psi / 241-276 kPa 145-160 psi / 1000-1103 kPa
75°F (24°C) 35-40 psi / 241-310 kPa 150-170 psi / 1034-1172 kPa
80°F (27°C) 40-50 psi / 276-345 kPa 175-210 psi / 1207-1448 kPa
85°F (29°C) 45-55 psi / 310-379 kPa 225-250 psi / 1551-1724 kPa
90°F (32°C) 45-55 psi / 310-379 kPa 250-270 psi / 1724-1862 kPa
95°F (35°C) 50-55 psi / 345-379 kPa 275-300 psi / 1896-2068 kPa
100°F (38°C) 50-55 psi / 345-379 kPa 315-325 psi / 2172-2241 kPa
105°F (41°C) 50-55 psi / 345-379 kPa 330-335 psi / 2275-2310 kPa
110°F (43°C) 50-55 psi / 345-379 kPa 340-345 psi / 2344-2379 kPa
Ambient temp is the outside atmospheric temperature.
INTERPRETING PRESSURE READINGS
Low-Pressure
Gauge		 High-Pressure
Gauge		 Action
Required
IN RANGE IN RANGE A/C is working properly.
LOW LOW Add Refrigerant.
LOW HIGH Need service, possible blockage of the
expansion valve or orifice tube.
HIGH LOW Needs service, possibly faulty compressor.
HIGH HIGH System is overcharged. Slowly remove
refrigerant. Venting is illegal in USA.
It is illegal to vent 134a refrigerant into the atmoshpere.