Q: Temp.gauge going to hot blowing cold air heat not working replaced radiator and thermostat still overheating 2005 Infiniti G35

Hi - sounds like you may have multiple problems with your engine cooling and passenger heating systems. It is possible that the cooling system has not been bled properly, and there is a large pocket of air in the engine/heater core; which would cause both overheating, and no passenger heat. Thoroughly bleeding the cooling system with the heater running full blast is the only way to correct this. A failure of the heater control valve, which allows hot engine coolant into the heater core for passenger heat, would cause some of these problems as well. I would recommend an overheating cooling system inspection by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.