Stop guessing. Put the leads where they go and read the number. Most electrical books teach theory. This one is has full-page component diagrams, one per part, showing exactly where the meter leads land and what the reading should be. Each page gives you the same four things: the diagram with lead placement marked, the meter setup, the expected reading, and what a bad reading actually means. Contactor coil reads OL? That page tells you it is burned open and what to check next. COVERED IN THIS GUIDE - AC systems: thermostat wiring, transformer, contactor, relay, dual run capacitor, control board, ECM blower motor, PSC condenser fan, compressor terminals, refrigerant pressure switches Heat pump: reversing valve coil, defrost control board, defrost thermostat and delay timer, heat strip control and snap disc Gas pack: control board and safety switches, 24V gas valve for natural gas and propane, hot surface igniter Plus a quick reference appendix with conversions, saturation pressures for R-410A and R-22, expected resistance ranges, and seasonal maintenance checklists. WHO THIS IS FOR: Apprentices who need to stop asking. Techs who want a second opinion in the truck. Anyone studying for EPA 608 or a state license who learns better from a diagram than a paragraph. Written by Gaston Davis, EPA 608 Universal, 25 years in HVAC and industrial refrigeration.
