[someguy321]

If you notice your fan motor or cord getting hot you can reduce the pressure differential (and therefore torque/load on the motor) by allowing some airflow to get around the filter- i.e. push the filter a bit to the side or add a tiny gap between the filter and the fan by sticking in a little block of wood.

This will come at a cost of filtration effectiveness (less airflow going through the filter) but will save your fan in the long run. Make sure not to let your gap or hole get too big or your filter will stop flowing enough air to work.

[Cthulhu_]

And of course, air will circulate through the fan multiple times over time so it doesn't have to catch everything in one go.