It sounds like the circuit board is faulty and for replacement we have the Replacement Printed Circuit Board part # MA10-04301k-v16 which should allow you to get your MaxxAir Vent Fan Model 4401K back up and running on the lowest speed setting. If you wanted to replace the motor as well while you were working on it we have this also, the Replacement 12-Volt Variable Speed Fan Motor part # MA10-20968. view full answer...