Upon arrival condenser operational air handler was not. Tech tested tstats (nest and Honeywell), no faults. Tech tested Honeywell zone control. Zone control passing only 14v. Tech deenergized zone control panel and reenergized. Zone control panel reset and operated correctly. As this is an internal intermittent fault occurring in zone control recommend replacement. Informed client, client requesting pricing. Office to follow up with pricing and availability. Unit is operational at this time.