W221 won't start.
 

Hello, first post, couldn't find answer by searching so I ask for your help.
2007 W221 S550 Automatic with 133k. About 10 minutes from my destination, i believe the AC compressor kicked off because it started blowing outside temperature air. At time to leave dwstination, car would not start. No clicks, no sounds whatsoever. Had it flatbed towed home and discovered front battery to be at 12.87v and rear battery at 11.77v so replaced rear battery with same ACM size H8 new battery.
still will not even attempt to start. Dash lights up as normal but turning the key does nothimg. Any ideas?
Thanks in advance, Bill

on mercs the AC and the engine cooling fan get to have a strange relationship.... if a signal from the engine ECU goes walkabout often the fan will run till the battery goes flat

I guess the clue to the doom came when the AC went strange....you're going to need someone with decent diagnostics and likely Merc skills to help - so make sure you stay well clear of a main dealer, they only know how to change the engine oil and clean it