Engine cooling fans will not come on?

The gauge should start to drop when the fans turn on and the coolant actually starts to cool off. Unless you are setting in very heavy traffic. That is on the Acadia, and your Traverse should act the same way. It sounds like you friends car might have an issue if the temperature stays really steady with the fans running.

Cleaning the TB should not have altered the cooling system parameters, but it would not hurt to double check the connectors around it and make sure something is not corroded or loose.

U need too check the cooling fan relay and fuse, if they are working than u could have a bad fan motor or a wireing problem need to check for power @ the fan motor with a test light or ohm meter a computer scan for trouble codes will tell u if u have a cooling fam switch problem hope this helps lsauto

Never heard of sanding the radiator? But if the fuses both in the car and in the power distribution box are ok and the fan relay is OK, check the ECT(electronic coolant temp sensor), If all is OK the PCM is not turning the fans on!