Car overheated when driving on the highway with AC on in a 90F+ weather.
Spewed out bunch of coolant as expected, but when I pulled over, the fan wasn;t working

When I pulled the plug from the temp sensor the fan didnt kick in.
Tested connection between relay and temp sensor and its OK.
Tested Relays - Both are OK

What else could it be?

 

better make sure your water pump and thermostat is working too, the fan isn't really needed at highway speeds

 

Can you turn the fan by hand (engine off)?
When the electric motor gives up the ghost, they are usually difficult to turn or won't turn at all.
Note: A stalled electric motor draws a lot of current, so you don't want the motor to catch fire