JMyers620

Please help! My 2006 V6 is having overheating issues. After reaching operating temperature it begins to bubble over through my coolant reservoir. I replaced my ECT sensor, water pump, thermostat, and a new radiator reservoir cap. I do not seem to have any other leaks other than through the reservoir cap. I know the fan is a 2 speed so I checked the 2 relays and fuses in the box under hood. All seem to be working and voltage is good to all. The fan comes on when I turn on AC but not on its own. What am I missing? Any help would be greatly appreciated.