HVAC technician explains how to read electrical schematics without getting lost. The letter C means different things on different parts: on a compressor it's the common terminal between start and run windings, but on a capacitor it's the common point between compressor and condenser fan. Always check the legend first.
Hey, are you new to the trades? Here's something you may not know about schematic symbols. The first time you open an electrical panel and look at that diagram taped inside, it looks like a foreign language. Squiggly lines, bells, circles with letters in them. Here's the secret: you're not supposed to memorize every symbol from memory on day one. Every schematic comes with a legend, and that legend is Read the legend before you read the circuit. Before you trace a single wire, find that legend and match up the abbreviations to the parts sitting in front of you. Now, once you're in there, watch out for something that trips up almost every new tech: the letter C. On a compressor, C is the common terminal between the start and run windings. On a run capacitor, C means something totally different. The common point between the compressor and the condenser fan. Same letter, different part. Same letter, 2 totally different meanings depending on what component you're looking at. Slow down, check the legend, confirm which part you're actually touching before you go grabbing wires. Now that you know, you can help someone else know.
