Found something interesting the other day while looking at something on my Civic when I took the plastic cover above the radiators off (will undoubtedly be the same on the Jazz).
The engine cooling rad runs the full width of the front and has both fans attached to it, the aircon radiator is very slim (this rad is on the high pressure side of aircon system) and sits in front of the engine rad, almost completely covering it. This means that the radiator you can see when you look through the cut-outs in the bumper is entirely the aircon rad, and it is the first line of defence for stones hitting the main engine radiator. Also explains why both fans have to operate when aircon is working, the aircon rad is creating hot air in front of the engine radiator so to prevent overheating and to have sufficient air passing through both radiators it needs both fan to be running.