Unfortunately no. It's a fixed speed. Had the dehumidifier on all night and still RH was 69 when I checked this morning. I'm having to water every other day because the soil is still damp from previous day. I'm sure this wouldn't be an issue if the air were drier.
How much do you trust your hygrometer and have you tried to calibrate it?
https://www.autoflower.org/index.php?threads/how-to-calibrate-a-hygrometer-check-accuracy.40740/