I'm told that you can get the blower motor though the radio/HVAC hole in the dash also the 5 series the e53 is based on. Look for a YouTube video. I was planning to do with one of ours I think I still have the blower but we sold the car before I got to it.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)