Originally Posted by hvaclmnop
You nailed it. It is impossible to be a good troubleshooter without understanding sequence of operation. Everyone that guesses at what is wrong with a piece of equipment is saying they do not understand (or possibly they do not want to understand) the sequence of operation of that equipment. Sure, a blind nut can find a squirrel now and then (oh...swap squirrel for nut ) but that's luck, not troubleshooting.
Apartment maintenance is a good place to get sequence of operation down pat. Listen and watch the furnace operate while you're changing filters on it and replacing the washers in the nearby bathroom sink. You should have that sequence memorized. When it doesn't do what you expect it to do, you'll have a strong foundation of where to begin looking for the problem.
Building Physics Rule #1: Hot flows to cold.
Building Physics Rule #2: Higher air pressure moves toward lower air pressure
Building Physics Rule #3: Higher moisture concentration moves toward lower moisture concentration.