I have a simple question that I cannot figure out. If it is cold outside, I have my A/C off and set the fan temperature to low why do I still get warm air (~75ish) from the vent?

I figured by setting the fan temp to the minimum no heat from the heater core will be tapped into and air should come directly from outside and be cold a frig.

What am I missing here?

Thanks in advance for not being an asshat.

oh yeah, drive a 2015 2.5L Subaru Outback.