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

BTW, to email someone on the board just click their username in the header in the message. It links to a login which in turn gives you email addresses.

Send flowers, chocolates, money if grateful...

Seriously, many people on this board contributed to the FAQ. If you have an idea for improvement or correction, kindly email me.

Steve, I'm not sure how to email you, but here are a few things I noticed that might make the path a bit easier for the next person:

1. Aside from the problem with the after-market radio, the plug holding all those vacuum tubes really doesn't have to be removed. In fact, I couldn't find a way to remove it, even using the info in the faq. It's possible some of the 740 MCC units are a bit different from each other; mine, for example, has a continuously variable fan speed (1992 740 wagon) (uses a potentiometer to effect this), and the vacuum fitting looked a bit too formidable to try to remove, so I just repaired the unit in situ. Nothing a long extension cord and my trusty Weller gun couldn't handle.

2. The trick is getting the board out. Once you unlatch the little metal tabs, there are still two screws going through the relay connector, so those have to be removed. Then the four screws that hold the PC board on. I lost two of them to the nether world of the transmission area, but two seem to be holding it fine. A good magnetic screwdriver would be a good idea, here.

3. The black plastic tray that holds the after-market radio (not sure if this is true for the factory unit) was a real challenge. Once I got the radio, its support cage, et al, out, I finally saw the two torx screws at the top holding it to the bracket. You must be able to get that whole apparatus out to reach the four ten MM bolts holding the bracket in that the two bottom screws of the MCC go through. Then the MCC will come right out.

4. Don't be afraid to put some heat on the relay pin and its surrounding trace. The old, bad connection (looks just like the picture in the faq - this is the only connection I re-soldered), needs a good bit of heat and definitely does need new solder added. Be especially careful that all the new solder you add doesn't form a bridge to the surrounding traces. I used a little desoldering braid to remove excess solder, and when the blob I'd added ended up with a little tip sticking up, I clipped it off close to the board with some electrical diagonal cutting pliers.

I don't know if this will hold up for a long time, or not, but it was so gratifying to hear the fan and compressor kick in after a few seconds delay, as they should. It's been a hot summer, and today's 92 degrees made me finally determine myself to get this done!

Thanks: I will update the information.