The R-134a and R-1234yf pressure charts are for guidance when using A/C Pro® recharge kits, refills, and gauges. The charts are intended to help provide an understanding of a vehicle’s air conditioning system pressure, which can be helpful during the diagnostic and recharge processes. Be sure to consult the instructions provided with your A/C Pro® product or our How-To section and Videos for more information.

R-134a System Pressure

Ambient (outside) Temperature
°F		 Standard Low Side Pressure Range
PSI		 Standard High Side Pressure Range
PSI
65 25-25 135-155
70 35-40 145-160
75 35-45 150-170
80 40-50 175-210
85 45-55 225-250
90 45-55 250-270
95 50-55 275-300

R-1234yf System Pressure

Ambient (outside) Temperature
°F		 Standard Low Side Pressure Range
PSI		 Standard High Side Pressure Range
PSI
65 28-38 135-154
70 33-43 145-159
75 38-48 149-168
80 43-48 173-205
85 49-58 220-243
90 49-58 243-261
95 53-58 266-289

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, possibly 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 refrigerant into the atmosphere.