The answer to 'evaporator coil making loud noise' is that a noisy evaporator coil is often caused by a problem with the blower fan or motor. This can be due to issues like a worn-out fan bearing, a loose fan, or a malfunctioning motor. The noise may also be caused by debris or ice buildup on the coil itself.
If the noise is accompanied by reduced airflow or the system not cooling properly, it's likely a more serious issue that requires professional HVAC repair. Attempting DIY repairs on the evaporator coil can be dangerous and may void your warranty, so it's best to call in a qualified HVAC technician to diagnose and fix the problem.