Does having low coolant level damage the air conditioner?

Static Pressure Test. An initial pressure reading indicates if the system has enough pressure to satisfy the low pressure switch and enable the compressor to operate. Most low pressure cut-off switches turn the system off at approximately 20 psi. Compressors will not normally function until the pressure reaches 45 psi. Therefore, you need a static pressure of at least 45 psi, before the compressor will normally operate. Static pressure is also used to determine if a system has enough pressure to begin leak testing (50 psi minimum). Too low pressure prevents the refrigerant oil from circulating through the system, which would damage the compressor. Therefore, since the system is not working most effectively, and oil is not circulating optimally, it's not good for the compressor's life.