The answer to 'why is my zone control system not cooling' is that there could be several common causes, such as a problem with the thermostat, the zone dampers, or the air conditioning unit itself. Symptoms may include uneven cooling, some rooms not cooling properly, or the system not turning on at all.
Some potential solutions include checking the thermostat settings and programming, ensuring the zone dampers are opening and closing properly, and verifying that the air conditioning unit is functioning correctly. If the issue persists, it's best to call in a professional HVAC technician to diagnose and repair the problem.