Customer said ac wouldn’t shut off and 1st floor was very cold. System is a 3 zoned system. 2 downstairs and 1 upstairs. Found that the upstairs stat was calling for cooling but the downstairs dampers were staying open causing the downstairs to get cold and the upstairs to not cool enough to satisfy the stat. Also found the zone board has a voltage drop across 2 zones potentially leading to them going bad. Would need to change zone board and dampers to correct system.