A new thing I have noticed on my 01 e39 after replacing a Chinese fan clutch with an OEM one, my aux fan runs more often now. It ran today after driving on the highway for about 20 minutes. I pulled back into my parking spot and I could hear the aux fan kick in. It sounded somewhat loud like a little lawn mower but quieter. The AC was not on and it was only about 73 degrees out. It ran for about a minute then shut off and them came right back on again, loud when first starting up. Is this normal?