Quote Originally Posted by Alexlind123
How does one go about checking for mouse nests? My fan is very weak and makes a noise deep throbbing noise when turned to full power, like that of a criuse liner's deisel engine. At three, the noise is not so prominent but the airflow is weak. Anything below three is useless. On an e28, the blower fan is where the expansion tank is on my car...
Change your microfilter for the weak airflow. As for the grinding/throbing sound, wait it out. It may be that when you change the filter it goes away, but if it does not a new motor may be in your future. This should be a long time in the future. Mine made racket for years before finally giving up. Quite a simple process and only about 200 bucks.