As crews finished running the power tools for their weekly check Tower 331 was dispatched to 2035 Pennsylvania street in company 32(woodlawn) first due for a reported chimney fire. Tower and Chief responded with 6 shortly after dispatch. Once arriving, nothing was evident from all sides, but crews continued to empty the ladder bed, laddering sides C,D,and B. Crew members then went to the roof to check the top of the chimney where it appears the cause of the call was from build up in the chimney. Crews cleared and were back inservice 1 hour later.