Overheating

First check coolant levels. Check radiator cap(s) for cracks (on radiator itself or overflow bottle). Let engine get up to temp, and check coolant flow - when engine does get up to temp, thermostat will open and hoses should feel pressurized with warm/hot coolant. Then try and determine if your cooling fans are turning on when they should. If not, you may have an engine coolant temp sensor or fan relay or module starting to fail. If it's not actually overheating when it shows it is getting too hot on the dash gauge, then you might just have a failing engine coolant temp sending unit. Most engines have two coolant temp sensors, one of the ECU and another for the dash gauge. You *could* remove the sending unit and test it with a pan of hot water and voltmeter (Google how). Of course to remove it requires draining some coolant. You could use that as an opportunity to perform some cooling system maintenance.

I keep having to put coolant every week in my 2006 Chrysler Pacifica but what can it be

I have one also just bought was doing same thing if ur floor is wet under your mats it's the heater core what mine started as dudr didn't fix it ended up splitting my radiator somehow fixed that it overheated so bad it messed up my head gasket also the thermo is stuck put blue devil in worked very good so far about to replace my thermo now will let u know dont recommend the blue devil but just spent my money on the truck needed a temp fix for now