The answer to 'central air making noise' is that there are several common causes, including worn bearings, a faulty compressor, or problems with the fan motor. Symptoms may include grinding, squealing, or rattling noises coming from the outdoor unit. Depending on the cause, solutions can range from simple DIY fixes to more complex repairs that require a professional HVAC technician.
If the noise is coming from the outdoor compressor unit, it could be due to worn bearings or a failing compressor. This often requires professional diagnosis and repair. Noises from the indoor air handler may be caused by issues with the fan motor or blower. In some cases, these can be fixed by a handy homeowner, like replacing a faulty fan belt. However, more serious problems with the air handler typically need an HVAC pro to service or replace the unit.