The thermostat does not control the fans, that is the job of the temperature sensor. (Strictly speaking, any switch that is controlled by temperature is a thermostat, but let's not be distracted by that as it is contrary to convention in cars.)
That the indicated temperature goes no higher than 70 without the fans suggests to me that either the thermostat remains open all the time or that the temperature reading is wrong. Does the temperature reading drop to the bottom of the scale when the engine is cold? Do you have a way to independently measure the temperature using a hand held infra red meter for example?
At this stage I can not say whether the ECON fault is related to the temperature fault. I suggest you ignore it for the moment, but bear it in mind if you get other indications of a general electrical problem.