This isnt for me, but my mom owns a 99 dakota 3.9 and she was telling me that she noticed the temp gauge going hot, but when she turned off the AC, the temperature went back to normal operating temperatures. The oil is at a normal level, and the coolant is full. The only thing I can think of is the thermostat. Any other ideas gents?

 

First thing that comes to mind is thermostat.

PS. give your mom creadit she pays attention to her gauges.