I had a Prius C 2013 before and it had the smell kind of smell whenever I turned on the A/C or just the fan. I took it to the dealership and they said it was because lots of dust was collected in there. Now I have another Prius C 2015 for just 4 months and I notice the same smell came back about a month ago. What could really be the cause? It smells so bad that I rather have the windows open instead of turning on the A/C.