As of March 2015, Kmart sells replacement electrical cords and filters for certain types of air conditioners. They also carry a number of accessories, such as wall sleeves and support brackets.
Kmart generally only carries parts and accessories for the air conditioner models that they sell. This includes various models from LG, Frigidaire, Coleman, Kenmore, Honeywell and Whirlpool. Both carbon and HEPA filters are available for some models. Replacement parts that require taking apart the air conditioner are generally not sold by Kmart and most likely have to be obtained from the manufacturer or a retailer that carries HVAC parts.