The answer to 'replacement making noise' is that a noisy HVAC replacement unit is often caused by issues like loose parts, worn bearings, or improper installation. Symptoms may include rattling, grinding, or high-pitched whining sounds. Solutions can range from tightening screws to replacing the blower motor or other components.
If the noise is persistent or getting worse, it's best to call in a professional HVAC technician to diagnose and fix the problem. Trying to repair it yourself could make the issue worse or even create safety hazards. A qualified technician can properly inspect the system, identify the root cause, and make the necessary repairs to restore quiet operation.