My 2005 Chevy Malibu Classic heater is working, but it is throwing out cold air and the air never gets warmer and the car don't overheat
Change the engine thermostat,may be stuck open.
Or you can check to make sure that the valve is opening to allow hot coolant from the radiator to flow to the heater core.
Could be low on coolant or you have a air pocket...
Looking for a Used Classic in your area?
CarGurus has 213 nationwide Classic listings and the tools to find you a great deal.
Search Chevrolet Classic Questions
Chevrolet Classic Experts