Why does one side of a 2002 Laguna dual heater only blow cold air?

If one side of a 2002 Laguna dual heater only blows cold air, it could be due to a few reasons. A common issue is a malfunctioning blend door actuator, which regulates the temperature of the air by controlling airflow from the heater core. Additionally, low coolant levels or a clogged heater core can also prevent hot air from reaching that side. Lastly, there may be a problem with the climate control system or a leak in the ductwork.