The client reported that the recently installed unit was not turning on and was blowing cold air with no heat in the home. Upon arrival, we found that the thermostat had a low battery warning, which the client replaced earlier in the day. A full inspection of the furnace was performed, including checking airflow and temperature rise, both of which were normal. The air filter had been changed just over a week ago and was still clean. The system was set to 70°F upon arrival and was tested by increasing the temperature to 74°F to check for overheating, but it operated normally and satisfied at 74°F. The client was advised to monitor the system and record any trouble codes if the issue persists for further diagnosis.