Just a note of thanks to the good people who put together the detailed FAQ, with pictures, explaining how to remove and repair my 740 Wagon's MCC panel. I ran into a few snags, but the biggest was that the previous owner had installed an aftermarket Alpine CD/Radio. There was nothing anywhere about how to get THAT out, and you can't remove the bracket that's bolted onto the wall and get the MCC out without removing the dang radio. I futzed with it, finally disassembling the thing from the inside out. There were two screws with Torx heads through the top of the black plastic sleeve thingie, and when I finally got down to those, it was easier.
The circuit board trace and bad solder joint was EXACTLY the one in the picture in the FAQ, right below diode D10. It even looked exactly like the picture! So, if your older Volvo Manual Controlled AC is getting squirrily, doesn't want to come on and stay on, etc., this just might be the problem.
Again, my thanks to the FAQ providers, as it has saved me over 400 dollars for a new MCC and install. Total time was an afternoon plus a bit, but I'm slow.

AC is working again. Now, just hope the re-solder job I did will hold!

Not sure how to post a link, but here's where I got the MCC repair instructions and pictures:

http://www.brickboard.com/FAQ/700-900/HeatingAirConditioning.htm#MCCClimateControlACNotWorking