2005 Ford Mustang over heating

In the engine electrical box there should be 2 fan relays a high speed, and a low speed, (should be indicated on diagram under lid) you can test these by using a multimeter set to 50vdc touch the black probe to ground (any metal bolt going into the chassis) touch the red probe to position 2 and position 4 when engine is warmed up and running, it should read 12-14 volts on one side all the time, and 12-14 on the other side when at operating temp, if you get voltage on one side but not the other then the relay has failed. Or you can just replace them and roll the dice. They run about 17.99 for the factory one, 25-40 bucks for aftermarket ones that are adjustable for temperature.