Still thinking, . . . . . Maybe you are expecting too much. If you run a 180 thermostat, all that does is set the MINIMUM temperature that the engine will run at. The electric fans are usually set to kick on at 200-220 an back off again when the temp drops to around 190-200. The fan must always be set noticably higher than 180, or the fan will constantly run trying to cool the engine, while the thermostat is trying to keep it hot.
So . . . If the thermostat is a 180, the the fan should come on at 200-220 ond off at 190-200. Maybe everything is alright and you are ok.
My fan will kick on at about 220 and off at about 190 if I am not moving (idling) or am stuck in traffic. But when moving with a constant flow of air, the fan never comes on and the temp is held to 180 by the thermostat.
Ed
