When Craig Pelton (Jim Rash), the dean of Greendale Community College, hears a mysterious thumping above the ceiling in Episode 1 (“Biology 101”) of the third season of this NBC (now Yahoo! Screen) sitcom, the study group explains it is student Troy Barnes’ (Donald Glover) pet monkey, which disappeared into an air-conditioning vent the previous season. But they know better. Soon, Ben Chang (Ken Jeong) bursts out of the ductwork in a terrycloth robe. Chang has been living in the ductwork since the college fired him for faking his credentials as a Spanish professor in Season 1. Young engineers looking for their first HVAC job should not consider this a viable housing alternative. In addition to being a bit dusty, ductwork is full of the nastiest sheet-metal screws (the sharp ends) imaginable. Perhaps someone should have informed Chang of this before he went into the duct after the monkey in Episode 21 of Season 2 (“Paradigms of Human Memory”):

So, if ductwork is not just your trade, but your home, consider exchanging Chang’s terrycloth for something made out of, say, Kevlar.

In Episode 6 of Season 3 (“Advanced Gay”), Troy, who previously discovered he has a preternatural talent for plumbing repair, is kidnapped by Vice Dean Robert Laybourne (John Goodman), head of the school’s shadowy Air Conditioning Repair Annex. As part of an initiation, Troy is the first to re-assemble a packaged window-mounted air-conditioning unit while blindfolded. Laybourne then takes Troy into the “room temperature room,” a totally enclosed space with nothing but pure, perfectly conditioned air. There is “no border between air and skin,” Laybourne explains as Troy looks around with trepidation. Although it would be unwise to argue with the man who played Daniel "Big Dan" Teague in “O Brother, Where Art Thou?,” the dean got it wrong. Only when room air is cooler than the skin will comfort result; a small temperature difference is the hallmark of a comfortable space. However, he is correct in describing HVAC knowledge as “a life of secrets you will not be able to share”—at least if what is hoped for is that first date.

In this fan-made compilation of clips, you can see how Troy’s Season 3 storyline plays out. In Episode 21, “The First Chang Dynasty,” Chang, who has risen from campus security guard to campus dictator, has kidnapped Dean Pelton and replaced him with a "doppel-dean-er." As part of an elaborate operation, the expelled study group, including Jeff Winger (Joel McHale) and Britta Perry (Gillian Jacobs) disguised as rock 'n' roll magicians and Troy and best friend Abed Nadir (Danny Pudi) disguised as plumbers, infiltrate Chang’s birthday party for himself. Their plan goes awry, and they are captured and held prisoner in the cafeteria basement. An air-conditioning fan is blocking their exit. Little do his fellow study-group members know that Troy cut a deal with the Air Conditioning Repair Annex, agreeing to join the school and leave his friends behind in exchange for help in rescuing the dean. The fan is stopped, and the study group saves the day. Troy makes good on his promise and joins the air-conditioning school. In Episode 22 (“Introduction to Finality”), Laybourne declares Troy "The Truest Repairman." Soon after, Laybourne dies from Freon inhalation while repairing an air conditioner, an apparent accident. Troy, however, suspects the new vice dean, Murray (Dan Bakkedahl), sabotaged and killed Laybourne. Troy challenges Murray to a battle in the Sun Chamber. Each man is enclosed in a space containing an out-of-order air conditioner. Each competitor must fix his air conditioner as the temperature steadily rises. The first to yield—or die from the heat—loses. Troy quickly fixes his air conditioner, cooling his space, while Murray struggles. As the temperature in his space rises to dangerous levels, Murray admits to killing Laybourne before passing out from heat exhaustion. Troy sees Laybourne's ghost and decides to save Murray by fixing his air conditioner.