IMHO, it is a bit a premature to pull the CCU. I would not do anything to the CCU yet as you have not found out what is the problem.

If I read your post correctly, you have 2 issues.

1) If the blower fan does not work, it could be the flat fuse. There is a fuse in a little black box outside the big fuse box. I once had a crack fuse and it was touching and breaking.

2) Are you getting heat but the compressor is working, i.e. the A/C hose is cold to touch but no cold air?

Good luck.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.