Why does my 2003 Monte Carlo ss's heater work sometimes?

If your 2003 Monte Carlo SS's heater works intermittently, it could be due to several issues. Common causes include a faulty thermostat, a clogged heater core, or issues with the blend door actuator, which regulates airflow. Additionally, low coolant levels or a failing water pump can affect heating performance. It's best to have a professional diagnose the problem to ensure a proper fix.