I would check to see if the fans are spinning properly. With the car in park and the engine running oh, turn the AC on full-blast. Both fan should be spinning. If not, you can replace the fan assembly. But first, I would have the battery checked and the alternator as failing components can cause similar symptoms.
Nissans are known for blown head gaskets. You can buy kit on Amazon that will allow you to check to see if that's the case. If that's the case you can decide if you want to put any more money into this vehicle. Nissan was a middle of the road manufacturer of automobiles until Renault bought them out. Now they have awful transmissions and blown head gaskets.