where does the “Circulation” fan option pull air from?

Question

I have my AC unit in my basement where it’s a constant 68°F, will the HVAC pull air from where it’s located downstairs and blow it through both the upstairs and downstairs zones if I set each thermostat to “circulate”?

I know that all it does is set the fan to low every so often to circulate the air, but where does it get the air from?

I’m also aware that it goes through air filters more often.

In: Other

Answer 1

I may be wrong but I’m pretty sure it pulls from the cold air return from inside your house.