That said, industry players like Lennox International Inc. LII and AAON, Inc. AAON have been benefiting from maintenance, monitoring and repairing services along with prudent cost-management practices. AAON, Inc.: Based in Tulsa, OK, AAON engineers, manufactures and markets air conditioning as well as heating equipment. Despite inflationary cost pressure, the BasX acquisition, which was closed in December 2021, has been delivering solid results for AAON.