Lennox furnace filter

[Ava]

I have an old Lennox furnace with a hammock style filter. The air flows up but the filter is at the bottom. One side of the filter is blue, the other side is white. I can?t figure out whether the blue side or the white side faces up.

[Imnukingfutz]

replying to Ava, Imnukingfutz wrote: white side towards the incoming airflow.