I have a 200 classic mounted to wall. I have had it for at least 5-6 years. the fans are buzzing and wondering how to tell if I have model with fan access in the back (without having to remove it) or if have to go through front chassis?
go to the very first forum page and search for classic fan replacement ( or something like that ). The search won't work right on any other page.
I haven't ever opened up a classic so can't give any advice but there are lots of posts about it .
https://midniteftp.com/forum/index.php
Larry
also look here for some info on Classic Fans
https://www.midnitesolar.com/faqList.php?faqCat_ID=57&faqCatName=Classic%20Charge%20Controller&parent_ID=2&subCatName=Troubleshooting