Display F3 on carrier Ac what problem
Well without a model number, I can tell you this. On some models, F3 indicates fan speed 3, which is high speed.If you push the mode button, these units will switch between f1, f2, f3 and smart fan. No problem.
On others, F3 indicates a fan speed error, either something is keeping the fan from turning, or there is a bad or loose connection somewhere.
On still other models, F3 indicates a freon leak or problem in the refrigerant circuit.
If carrier made their own units, they would probably act the same, but they don't. Model number is important, since the unit could be a daikin, LG or Samsung under the skin...