(1) TCC AC Maintenance - TRANE - 410A - tested high and low voltage components ok, inspected air filter dirty supplied and replaced 14x30x1 air filter, checked evaporator coil and cleaned, chemically cleaned coils and tested primary drain pan, while testing primary drain pan noticed that sewer system has a slow blockage that will only get worse. Noticed small amounts of water back flowing into unit. Spoke to client about reviving plumbing service will have the office contact client to schedule to unclog drain. Checked delta T ok receiving good temperature split, checked safeties ok, noticed indoor unit zoning panel has signs of corrosion, board currently operational, checked condenser pressures noticed Evap below freezing, checked capacitor ok checked contactor ok electrical components within range, sprayed and washed down condenser coils, Unit is currently operational and cooling at this time, Follow Up Action: Office to contact client to schedule Plumbing service for restricted pipin