The answer to 'zone control system blowing cold air' is that there are several common causes, including a failed zone damper, thermostat issue, or problem with the zone control board. Symptoms may include inconsistent temperatures, some rooms getting too cold, and the HVAC system running excessively. Solutions can range from adjusting thermostat settings to replacing faulty zone components.
If the issue is with a specific zone damper or thermostat, a DIY homeowner may be able to troubleshoot and fix the problem. However, if the issue is with the central zone control board or requires extensive diagnosis, it's best to call in a professional HVAC technician to inspect the system and make the necessary repairs.