Read the Wiring Diagram Before You Probe

Every piece of equipment has a wiring diagram, usually on the inside of the access panel. Before you start probing wires, take five minutes to actually read it. Identify the circuits, trace the path from the thermostat signal to the contactor, and understand what should be happening before you test what is happening. Five minutes of reading saves thirty minutes of guessing.

Photograph the wiring diagram and attach it to the equipment record in PrecisionOps. Diagrams fade, get painted over, or go missing entirely over the life of a unit. Having a clean copy in the equipment history means the next tech -- or you, two years from now -- doesn't have to hunt for it online or call the manufacturer.

This is especially important on older units or equipment with aftermarket add-ons where the wiring may not match the factory diagram anymore. Document what you find.