AC low pressure shutoff sensor?

I have a 5 year old Lennox Elite HVAC. So far the AC is cooling just fine but I have a concern. Do home HVAC AC systems have a low pressure sensor that detects low refrigerant pressure and keeps the compressor off when the pressures are too low...similar to a car AC? I'm asking because my AC has a sight glass in the refrigerant line and I'm seeing a fog of air bubbles for about 15 seconds as the compressor turns on plus I'm smelling an oily smell (the wife says it smells like onions) now and then by the HVAC closet. I've called my regular AC repair business for an appointment but they say they are swamped and have us on a list if a cancellation pops up. If a low pressure switch keeps the AC off that's one thing but if there's no sensor do I need to worry about my AC compressor destroying itself due to low refrigerant?

source https://hvac-talk.com/vbb/threads/2240612-AC-low-pressure-shutoff-sensor?goto=newpost