There are a few different synonyms to use in place of the term "central airs". One option is "central heating and cooling", which encompasses both components of a central air system. Another possibility is to simply use "HVAC system", which stands for heating, ventilation, and air conditioning. Additionally, the term "climate control" could be used in some contexts to refer to a central air system. Ultimately, the choice of synonym will depend on the specific context in which the term is being used, as well as personal preference and writing style.