Hi,  I have a 2016 toyota tacoma V6, on hot days when we are stuck in long lines in traffic or waiting on a drive through , while the truck is on D, the needle of the temperature moves to the hot part ,  it has never crossed to the red side but goes 3/4 to the maximum normal temp,  the AC stops cooling and I have to move to transmission to Park and rev up the engine , to get the AC working again and the needle to go back to the middle of the gauge.

I Took it to the dealership and they said everything looks normal ( thermostat, fans, coolant, etc) ,  but it doesn't seem like it ... any thoughts?  I really like my truck , it only has 68 K mostly city Miles.

Thank you for your help