Fan runs when required by engine temp. It usually switches on at about 225-230 farenheidt. This is normal. Also if you turn on the AC the fan will run , and IIRC that one will have 2 speeds and is dependant on condenser pressure. But forget that for now, If your moving down the freeway at 60 mph the airflow at the radiator is good enough that even on an 85-90 degree day the fan wont run, but when at Idle, when there is no airflow the fan should activate. Usually about 3/4 gauge is where it will come on, however gauges arent allways accurate.
You could have a trapped air bubble in the system. There are 2 air bleeds I think, one at the bypass and one on the top outlet.I have in the past , pulled a heater hose off and filled through it to be sure all the air was bleed out, just to speed up the process.Chances are by now , if you have driven it and it has cooled down, all you will need to do is add some tothe expansion tank(what the rad cap goes on to) and you will probably be good to go.
I would check the atual temp of the water at the water outlet verses the reading on the gauge to be sure it is reading correctly, then you will know for sure.
You can check the coolant temp with a good data scanner, look at live data stream, and watch it. I have an extra coolant sensor in my tool box that I use , i plug it in to the cars harness, then turn on the key and look at the coolant temp. ThenI hit it with a bic lighter or propane torch, watch the temp go up and wait for it to hit 235 ish, usually by then it will send a cooling fan request and the fans kick on. Takes a lot of time waiting for it to warm up out of the equation, and if the car has a defective sensor the motor is still cold enough to work on.