03 Mazda protege cooling system problem.

[03protege_]

okay my girlfriend has 03 MP and in october of last year she said her radiator exploded. i was told everything got replaced except the CAT converter. and recent it has been overheating. i figured that its was just the arizona heat. but it is overheating way to quickly. so i flushed the radiator and replaced the thermostat. figured that was it but it is still overheating. so i think it might be the water pump. i just dont know what else it could be.
anyone have any ideas? plz help.

 

[concept]

It could be the electric cooling fan switch. When the coolant temperature gets high enough, the fan should switch on. If it doesn't, the coolant temp switch is bad or the fan is bad, but I'd be more likely to guess that the switch is bad. A mechanic would monitor coolant temps while watch for fan operation.