AAON Inc. AAON, Inc. manufactures heating, ventilation, and air conditioning equipment for commercial and industrial indoor environments. AAON is headquartered in Tulsa, Oklahoma and has manufacturing facilities in Longview, TX, Parkville, MO, and Redmond, OR. AAON employs approximately 4000 people across four US-based locations and has annual sales in excess of $880 million. Wikipedia