You've most likely got a 50/50 chance with this. There is an NTC temperature sensor in the filter duct, which may be playing up. This is a "Negative temperature co-efficient" device - the hotter it gets, the lower the resistance. It operates in the kOhm range on your multimeter. If you can prove continuity from the sensor to the pcb and the sensor itself is functional, the pcb is at fault.