Attempting to charge an A/C system with only a low side guage is like trying to perform brain surgery with one eye covered - NO DEPTH PERCEPTION.
If you're trying to do so, forget it and go get a set of manifold guages so you have the proper perspective on what the system is doing.
When looking at only the low side, it is common for:
1) static pressure to be upwards of 100 psi when the compressor clutch is not engaged,
2) readings of 60 psi and greater when the valve to the can is open (you're reading the can's pressure, not the system)
3) under or over charge the sytem since it is virtually imposible to guage the state of the system's charge based solely on the low side reading.
Steve
