2010 malibu. At random, ac stops blowing cold air. Still blows but not cold. At the same time, the temp gauge drops to the bottom. It can work for a day fine then suddenly do the same thing. I've watched my temp Gauge flutter a couple if times and I can feel the change in temp. Please help....it's hot in Florida!
It sounds like there is a wiring problem with the coolant temperature sensor.
It is difficult to say whether it's a short or open but wiring none the less. When a wiring problem is detected, the car goes into a limp mode. It sets the internal temperature to 70 degrees F. This makes the gauge drop. It runs the radiator fans full blast all the time and it shuts off the AC to keep the thermal load to a minimum. I also bet the check engine light is on.