Complete 1 system a/c repair and preventative maintenance check. the system works ok, upon completion, blower components ok, changed filter, flushed condensate line and installed overflow protection, checked operating pressures, superheat and subcooling checked a/c components. Coil clean. When pm was completed, downstairs thermostat lost power due to loose telephone jack connection to zone board, secured wire connection, the thermostat was powered but found bad damper which was not fully. Provided an estimate to replace it but the client said he had homeowner warranty, he will call them to replace it. Signed up for comfort club membership and did first a/c visit.