Cooling fans not operating, causing overheating.

You can check if your fan works by running a 12v with a ground hooked up to the fan. Make sure the fan is disconnected from the rest of the system to just test the fan. If the fan doesn't come on when the car reaches the temperature where the fan is supposed to kick on and it doesn't, check the fan switch and relay. If those all work, check the thermostat and make sure your cooling system doesn't need to be flushed.