Help needed with volvo B10M coach

this machine wont put air to any of the airbags when she is started. Any ideas about how to solve or what the problem might be?
I thought it might be the brain so i tried another one on loan to no effect. She is filling the clocks ok, and a while back she would fill the bags on one side but not the other. She does’nt seem to be putting the power to the brain to the airbags. Any help much appreciated

Don’t know how old your machine is but I had a fair bit of grief from a '98 FL - rear bags would not fill - changed solenoid valve above rear axle - looks like a solid aluminium block with about 7 pipes attached.

Ours failed because some ding dong (probably with bicycle spanners) messed up the receiver drier and the system became saturated over time with condensation. I got half a cup of water out of each airbag when I changed them.

We changed the drier, 4 way and the above solenoid and all is well.