9688。 Yongzi air compressor is a machine produced by Wanzi Vegetable Compression Machinery Co., Ltd. According to official website of Wanzi Vegetable Compression Machinery Co., Ltd., the maintenance password of Yongzi air compressor is 9688. The manufacturer sets the password in order to better maintain the machine and automatically change the operating parameters of the machine, which is cost-effective. Wanzi Vegetable Compression Machinery Co., Ltd. is a large-scale enterprise integrating R&D, production, sales and Internet, headquartered in Jiading District, Shanghai.