I am sure by now you have read enough on line here to know that you have a mechanical wax valve interface between your engine's need for cooling and the hydraulic fan motor. Engineer Mike has covered this at length in a number of posts. These wax valves seem to vary on specs as to when the fan will activate. The specs suggest a minimum fan speed regardless of engine temp but the fan on my 03 ISL400 remains motionless until the engine is close to ops temp. Since your engine remains at about 185 and never overheats--it sounds like all is well. However, since there is no interface between the wax valve and your dash A/C, your A/C condenser on the radiator stack will not always get adequate air flow, except during fairly warm ambient temps/engine op temps. Not so bad if you live up north, not so good for us folks down south.
2003 40' MDTS
Garden Ridge, Texas