Why does your 2003 highlander heater blow cold air?

A 2003 Highlander may blow cold air due to several potential issues. Common causes include low coolant levels, a malfunctioning thermostat, or a blocked heater core. Additionally, problems with the heater control valve or the blend door actuator can prevent warm air from reaching the cabin. It's advisable to check these components to diagnose and resolve the issue effectively.