The answer to 'why is my zone control system making loud noise' is that it is likely due to a problem with one of the system's components, such as the dampers, actuators, or control board. Loud noises can indicate issues like a failing motor, worn bearings, or mechanical problems that are preventing proper operation of the zone system.
Common symptoms include banging, rattling, or screeching noises coming from the vents, air handlers, or control panel. This can be caused by dampers not opening and closing smoothly, actuators malfunctioning, or other mechanical failures. It's important to address these issues promptly, as continued loud operation can lead to more serious damage over time.