If your air conditioning unit has an "emergency" setting or indicator, it typically means that the unit is operating in emergency heat mode. Emergency heat mode is a backup heating mode that kicks in when the primary heating system is not functioning properly or when temperatures are extremely low.
In emergency heat mode, the air conditioning unit will use electric resistance heating to generate warmth, rather than relying on the heat pump's normal heating cycle. While this can provide some heat to your home, it is less efficient and can be more expensive to operate than the primary heating system.
If you are unsure why your air conditioning unit is in emergency mode or if it is not functioning properly, it's best to contact a professional HVAC technician. They can assess your unit and determine the underlying issue, whether it's a malfunctioning primary heating system or a problem with your air conditioning unit. They can also advise you on the best course of action to restore your system to optimal performance.