Yup, it's a pain in the butt.
Remove the little plastic clip that holds the vacuum lines beside the brake booster -- this will reduce the amount a skin removal considerably.
You will have to get either a thinwall 10mm socket on there or use a short 10mm on it, nothing else will work. Have a care not to drop the nut, it will vanish down into the darkness. I never did find mine, had to use a spare.
Once you get that nut off, you must also remove the clamp on the low pressure hose further down to pull the manifold off the expansion valve.
Underneath are two 4mm (I think, may be 3mm) flathead screws that hold the expansion valve to the evaporator. Use ONLY a good hex driver that fits securely, if you strip these you are screwed. I used a plain hex key from a cheapo set, but it fit securely. If you have a swivel, you can use a hex driver on a 1/4" drive, but you will want to cut the key off short so that you can get it all the way into the screw and completely seated.
Not the best design I've ever seen, very difficult to reach.
DO NOT overtighten the screws going back in, they will be stuck something fierce then next time you have to do this!
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!