2016 Grand Caravan RT going to 3/4 hot then back to half

If it only does it once after the initial start up it’s the new thermostat slightly sticking. if it does it continuously then you could have an air pocket in the cooling system.

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Maybe it's the $12** piece of crap thermostat from auto zoo ? Or an air pocket Because that's what it sounds like , your " mechanic " should know this , and they should have done some testing before replacing parts you didn't need ie. compression test , bleed the system . That thing is a money pit

If it's overheating at slow speeds or while idling, like waiting in the bank drive through, it's an airflow problem. Such as the radiator cooling fans not working properly, a dirty air conditioning condenser, or a missing fan shroud. If it's overheating at higher speeds it's a coolant circulation problem. Water pump, thermostat, cooling system clogged with rust and junk, air trapped in the cooling system, or the lowerradiatorhosecollapsing. Since the mechanic just replaced the radiator I'd suspect air trapped in the cooling system. Does the heater blow hot air? If not, that's a good sign of poor coolant circulation. Jim