A/C

 Ambient Temperature in °F Low side Pressure Gauge reading and High side Pressure Gauge reading

65°F Ambient temperature: 

Low side pressure 25-35 psi High side pressure 135-155 psi

70°F Ambient temperature: 

Low side pressure 35-40 psi High side pressure 145-160 psi

75°F Ambient temperature: 

Low side pressure 35-45 psi High side pressure 150-170 psi

80°F Ambient temperature: 

Low side pressure 40-50 psi High side pressure 175-210 psi

85°F Ambient temperature: 

Low side pressure 45-55 psi High side pressure 225-250 psi

90°F Ambient temperature: 

Low side pressure 45-55 psi High side pressure 250-270 psi

95°F Ambient temperature: 

Low side pressure 50.55 psi High side pressure 275.300 psi

100°F Ambient temperature: 

Low side pressure 50-55 psi High side pressure 315-325 psi

105°F Ambient temperature: 

Low side pressure 50-55 psi High side pressure 330-335 psi

110°F Ambient temperature: 

Low side pressure 50.55 psi High side pressure 340.345 psi 

 Low side / High Side

 Low Side 25-40  / High Side 170-250 Normal Pressure affected by ambient temp- 

 Low-Low Side /  Low-High Side,, Under Charged -

 Low-Low Side  / Low-High Side,,  expansion valve Restricted or closed -

 Low-Low Side  / Low High Side,,  Orfice tube Restricted or blocked -

 Low-Low Side  / Low-High Side,,  Suction line at pump Restricted or blocked -  

 Low-Low Side  / Low-High Side,,  Condenser Line to Evaporator, Evaporator  Restricted - Low-Low Side  / High-High Side,, Evaporator Restricted Air Flow -

High-Low Side / Low-High Side,, Compressor weak, High side needle will shake -

High-Low Side / High High Side,, Over Charged 

High-Low Side / High High Side,, Splash  water onto Condenser-if press drops,, Over Charged  -

 High-Low Side / High High Side,, Condenser Air Flow Restricted  -

 High-Low Side / High High Side,, Engine overheating Temp High -

 High-Low Side / High High Side,, expansion stuck Open -

 High-Low Side / High High Side,, Air, Moister in freon