Is your problem that the fan is running when it oughtn't, or that the compressor isn't running when it ought? Naturally if the thermostat is set to a temperature higher than the ambient temperature, the cooling unit should not run; and it's entirely possible (and good) that there's a delay of a couple minutes before it will let the A/C start up again after it shuts off to let the pressures in the cooling system equalize.
If you think the fan should shut off, perhaps the thermostat has a fan switch set to "on" rather than "auto." It's also possible that the fan may automatically run for a little bit after the compressor shuts down since the evaporator is still cooling for a bit...I don't recall if my Duo-Therm does, and even so it would not be a direct comparison as it's a different and older model.
