The word vacua is a plural of the word vacuum, one definition of which is a vacuum cleaner. While I imagine that the plural vacua is usually reserved for referring to multiple spaces devoid of matter, can it also be used to refer to multiple vacuum cleaners?
Vacua as a plural of vacuum (cleaner) would be incorrect.
In vacuum cleaner, cleaner is the noun, and vacuum is an attributive noun (a virtual adjective) specifying how the cleaner works, (compare: whisk broom, push broom, diesel engine, etc.). Note that vacuum is singular, as are most adjectives. Only the noun receives the suffix 's'.
Since vacuum is short for vacuum cleaner, it's pluralized the same as the term it's short for.