Over heating /cold air
Have you checked the coolant level?
Thermostat might need to be replaced. It's either stuck open or shut. They are usually pretty cheap and are easy to install.
In addition you may have air in the cooling system. These systems need to be bled when refilling. HTH. -Jim
Looking for a Used Impala in your area?
CarGurus has 35,546 nationwide Impala listings starting at $899.
Search Chevrolet Impala Questions
Chevrolet Impala Experts