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 commercial hvac installation & replacement, bring intermittent operation and controls into the scope discussion. Compare options on complete scope, planned interruption and serviceability. State what existing work is retained and which building or electrical changes are excluded, rather than presenting an equipment-only price as a turnkey project.