malfunctioning vs functioning

malfunctioning is not a noun while functioning is a noun.

Word	Noun	Adjective	Verb	Adverb
malfunctioning	No	Yes	No	No
functioning	Yes	Yes	No	No

malfunctioning (noun)	functioning (noun)
	process or manner of functioning or operating

malfunctioning (adjective)	functioning (adjective)
not performing or able to perform its regular function	performing or able to perform its regular function