Chengdu, Sichuan trip.

Do you mean the Wanjiang Campus of Sichuan University? If so, it is about 20 km from the airport. At the airport, you can take a taxi to the bus stop of new Campus of Southwest University of the Nationalities. There you can take bus no. 306 and get off at New South Road Station, then walk to Sichuan University in several minutes. If you take a taxi, it costs about CNY40-45.
During the Mid. of September in Chengdu, it may be cool, sometimes it has frequent rain, but not heavy. You can prepare the long-sleeved clothing and a light overcoat.