my coupe makes wired hissing noise when the air blow is set to low.
I have a digital climate control and when the power of blow is set to 2-3bars and I started to hear hissing noise.
The hissing noise is gone when it's full strength but when I lower down the air blow then hissing noise comes back.
What could be the problem with this noise??
It happens both air condition and heater. (100% it's not from pullys or belts)
Thanks in advance