R-134a System Pressure and Temperature Relationship Chart

R134a Pressure Gauge Chart

Ambient Temperature (°F)Low SideHigh Side
110°50-55 psi335-345 psi
105°50-55 psi325-335 psi
100°50-55 psi300-325 psi
95°50-55 psi275-300 psi
90°50-55 psi250-275 psi
85°50-55 psi220-250 psi
80°45-50 psi175-220 psi
75°40-45 psi150-175 psi
70°35-40 psi140-165 psi
65°25-35 psi135-155 psi

 System Pressure Troubleshooting

Low Side and High Side Pressures are Low
• Refrigerant charge below manufacturer specification
• A/C compressor not engaged / variable displacement inoperable
• A/C compressor performance deteriorating

Low Side and High Side Pressures are High
• Refrigerant charge above manufacturer specification
• Condenser fan inoperable
• Condenser dirty / airflow obstruction
• Internal obstruction of condenser

Low Side Pressure Low, High Side Pressure High
• System restriction

Pressures at or Near Equal
• A/C compressor failing internally
• A/C compressor variable displacement function inoperable
• Expansion valve failure

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