Performed preferred customer furnace cleaning. Cleaned the burners and the flame sensor. Checked the furnace heat exchanger. Wiped down the inside of the furnace. Cycled the furnace. Checked the motors for proper operation. Cleaned the drain trap. Performed furnace combustion test. The is running normally at this time. The customer was experiencing condensation on the ductwork near the fresh Air equalizer duct. Adjusted the balancing damper. They will see if that works. Also we were here to repair the exhaust vent on the water heater. The customer was wondering if we could do anything about the rust on the water heater and would like a call from Jeff.