and on...
remove bottom cover. Three tabs (yellow circles) and then it hinges off.
With the front finally off, the fan switch unit can be removed -- squeeze tabs together gently jsut until they clear and the unit can be removed. It unplugs from the side of the ACC like the temp wheel did.
Phew. Now the cover hinges up and off from the guts. The black plastic side pieces that fit over the pins slide off over the pins. Leaving you with...
..this. Well, not
exactly this, I forgot to take pictures of the inside of the w123 ACC unit when I got this far, so here's a picture of my w126 practice unit. The w123 ACC has only four relays and the circuit traces are different, but otherwise it looks the same. In this picture you can see the four circuit boards that make up the unit -- the main board on the bottom, the daughter board above it, sandwiching the button switches, and the two side wing boards.
And here's what a cracked solder joint looks like. All of these are cracked. I even slipped a piece of paper in between one to demonstrate. For me, these were visible with only the bottom removed, but others have reported that the button switch solder joints on the daugher board sometimes break, and you can't get to them without a full disassembly.
I did a detailed writeup of this over on a blog (
http://w123maintenance.blogspot.com/) in case anyone is interested. Nobody reads my blog, I'm just using as a convenient place to document stuff for myself.
hope this helps
