The answer to 'emergency HVAC service making noise' is that there are several common causes, including worn bearings, a loose fan, a malfunctioning compressor, or a problem with the blower motor. These issues can cause unusual sounds like grinding, squealing, or rattling noises coming from your HVAC system.
Some symptoms of these problems include reduced airflow, uneven heating/cooling, and increased energy bills. In many cases, it's best to call a professional HVAC technician to diagnose and repair the issue, as trying to DIY HVAC repairs can be dangerous and may cause further damage. A qualified technician can quickly identify the source of the noise and make the necessary repairs to get your system running smoothly and quietly again.