delkay4000

Hi, new member here.

I recently bought a 1996 SL500 R129. After it had a service at a local garage the blowers wouldn’t switch off even when the key was removed. I tracked this down via a few threads to the blower regulator having failed. I bought an after market one from Autodoc in Germany. The original had obviously previously died and so I was replacing a failed after market regulator with a new one. I was pleased to find I managed to get the regulator replaced and everything seemed to be fine. Then I noticed that whilst driving the centre vent seems stop and start blowing air, whether it’s in auto or manual. There is a strange creaking noise, like a tiny spooky door being opened, and the air will stop, after a while it will restart.
Two questions I guess, 1. Is this how the ventilation system is controlled normally, and 2. Any idea what the creaking spooky door noise is and how I can stop it?

thanks in advance.