I have a customer with 2 zone single stage heat/cool forced air system. The model of the control board is the MABS-V-3. There seems to be no literature for this model anywhere! The specific question I had was does zone 1 serve as a "master" zone? In other words must it be calling for cooling before any other zones can open? This system seems to only allow zone 2 to cool if zone 1 is actively calling. Zone dampers work fine, but wondering if this is normal operation or not. Master selector switch is in cool as well. Any insights or links to the manual would be greatly appreciated.