Can refrigerant get low without a leak?

No, refrigerant inside a residential or automotive air conditioning system can never get low without the presence of a physical leak, because cooling systems operate as completely closed, hermetically sealed loops. Unlike engine oil or gasoline, which are consumed or burned during normal mechanical operation, refrigerant is designed to circulate continuously within the sealed tubing, coils, and compressor without ever being naturally depleted or consumed. If your air conditioning system is low on refrigerant, it is definitive proof that a physical breach, crack, pinhole puncture, or failed seal exists somewhere in the closed loop, allowing the pressurized gas to escape into the atmosphere. Simply recharging the system with more refrigerant without locating and repairing the underlying leak will only provide a temporary fix, as the gas will eventually escape again. You can verify that a leak is present when pressure gauges show a drop over time.