During a service call for a Rheem Classic Series, the AC was completely unresponsive. I checked the electrical panel and found the system's breaker had tripped. After resetting the breaker, the unit still wouldn’t start, so I inspected the thermostat and found a faulty wiring connection. I repaired the wiring using wire nuts and re-secured the connections. After restoring power, the unit started but was still low on refrigerant. I recharged the system with R410A to proper specifications, restoring full cooling functionality to the Rheem Classic Series.