Needing Advice On Overheating Problem

[AirmanSharpley331]

Hey fellas newbie to the forum here just looking for a little advice sorry for the long post in advance

Noticed my lexus had ran hot one day while in stop and go traffic turned the heater on got parked no big incident, it overheated again once but just barley and i noticed it only overheated when i was in stop and go breaking and constant shifting traffic so i just assumed thermostat, replaced the thermostat (non lexus thermostat not sure if that matters or not) and still noticed it overheating. i then noticed then radiator fan wasnt kicking on when the engine got up to normal/overheating temp but it would come on when i turned the A/C on so i figure the motor isn't bad, i burped the coolant system in case there were any air bubbles, i've checked the fuses non of them are blown, and the relays are all good, i'm pretty stumped to say the least lol. So i figured either i got a faulty thermostat (seems unlikely though since i got it brand-new) or the lexus is picky and needs a lexus thermostat since the other one may not be opening at the right temp can anyone give me any suggestions?? any help is GREATLY appreciated

[AirmanSharpley331]

Also i'm not certain if the radiator fan runs injunction with the thermostat some kind of way to know when to cut on i figured some cars are like this but i'm not sure if a lexus is one of em

[lexusis200x2000]

There should be a sensor bolted to the rad which turns the fan on and off.

On most cars u can bridge the wires in the plug to test it.