In this troubleshooting problem, it’s the middle of July, and you are the follow-up technician on a callback. The equipment is a standard 3-ton package unit, a/c with gas heat, 208/230, single-phase residential installation. The original complaint was a “no cooling at all” call, and the technician who preceded you on this job (we’ll call him Technician #1) has only limited experience, but he reported correctly that he found a failed transformer and replaced it.
He’s only been gone for two hours, and the customer is calling back to say that the unit is out again, and the house is warming up. When you arrive, you find the following conditions: