HI Yes we to have a 2016 sig nav 4x4 and yes we have had exact same problem last winter. I took it to dealer who needed to do a test drive with a clip attached which confirmed no airflow to screen. New unit ordered fitted a couple of weeks later, one day to fit, dash out i believe ??? Just to add the unit made some unusual noises a while before i noticed it was not working to screen (loud thumps noise as baffle plates moved ) above work all done under warranty free of charge. 4 years warranty march 2016 uk reg car
JC
