Why wont the heat and defrost work in my 2008 Chevy impala?

If the heat and defrost in your 2008 Chevy Impala aren't working, it could be due to several issues. Common causes include low coolant levels, a malfunctioning thermostat, or a faulty heater core. Additionally, problems with the HVAC controls or blower motor can prevent warm air from circulating in the cabin. It's best to have a mechanic diagnose the issue to ensure proper repairs.