Interior unit The evaporator coil fits In the furnace plenum. The plenum may be the area in the furnace on either facet on the air handler, in which air is brought in and despatched back out into your house. Seal up the opening inside the wall utilizing expanding polyurethane foam. https://airconditionerinstallatio77420.total-blog.com/the-air-conditioner-installation-diaries-54813926