Cockpit fan noise
I own a 2001 Saab 93 convertible that has an annoying fan type noise coming from under the dash. It sounds like a slow moving fan blade hitting something. It only occurs when the car is running and it's controlled by the AC/heater blower switch. I've removed oiled and replaced the Cabin Air Sensor unit. I also confirmed that the noise still occurred while the Cabin Air Sensor was removed. I have removed the cowling and checked the AC/heater blower fan to confirm that the noise still occurs even though the fan isn't moving. It's a constant speed noise that isn't affected by the blower speed control and only occurs when the car is running. What the heck is it?