What do C, H, S, F stand for? June 30, 2023 01:57 Updated C, H, S, F are the letter symbols for the Gradient unit’s modes. C = Cooling H = Heating S = Smart F = Fan Only Related articles Gradient Indoor Unit Maintenance and Cleaning What do AU, LO, MD, and HI stand for? When can I buy the Gradient? What are modes? How do I use the Comfort Control Dial?