Heater blows air when the AC/heater is not on

Hello

It sounds like you have a re-circulation air blend door actuator that is not working. To confirm lets remove the unit to check the operation. here is a guide that will help walk you through the steps and diagrams below to how you how on your car:

https://www.2carpros.com/articles/replace-blend-door-motor

1 - Mode Actuator
2 - Air Plenum
3 - Evaporator Temperature Sensor
4 - Mode Actuator (Side View)
5 - Air Temperature Actuator
6 - Recirculation Actuator
7 - Blower Motor
8 - Blower Module
9 - X202

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.