I was troubleshooting a system yesterday. Family had been without air for 3 days (95 in house). Went up to attic to check door switch on furnace. At the top of the attic drop down stairs were 3 ducts running across as to allow NO access to unit without crawling over them. Finally squeezed over them and sure enough someone had TAPED the door switch down and the heat had melted the tape off. Put the doors back on, crawled back over the ducts, fixed ducts and went home. Why install this way?