Follow the symptom from thermostat to equipment
For Rosemont service, note whether the thermostat display is active, whether the fan runs and whether heating and cooling behave differently. This gives a clear starting point without requiring a homeowner to test live electrical components.
If the system works intermittently, record when it stops and whether the thermostat still calls. A repeatable description is more useful than replacing a thermostat solely because the room feels uncomfortable.
For vrf / vrv systems, bring intermittent operation and controls into the scope discussion. Discuss the specific fault, compatibility and service support before comparing repair with alteration or replacement. Keep unsupported equipment and chiller systems outside the promised scope.
