Air con not working.

Re the scan- VCDS the engine controller asks you to check the A/C controller because it isn't getting the correct response it expects from it.

I haven't seen that particular A/C controller code before but when you combine that with the single wire CAN fault codes that appear in multiple controllers I'm wondering if there could be a link.

Because your bus is a Caravelle I think it has that feature where when you select reverse it switches the cab heater to recirc, and since the recirc feature is part of the heating system it probably comes under the 'Comfort' system which is run by the unit under the drivers seat in your year van.  It is shown as address 46 Cent Conv on your scan.  Cent Conv problems can sometimes be caused by wrongly wired aftermarket radios so it's safest to disconnect any radio that is not original where Cent Conv codes are present just to eliminate the problem.

Single wire operation means that the CAN system is working in a limited fashion.  It could be caused by a broken CAN wire somewhere (CAN wires are the small gauge wires you will see twisted in pairs.  They carry data between controllers.  There could be a fault to cause this code in a controller including the CAN Gateway itself which is part of the dash cluster on your van.

1.  I would start with the full fuse check

2. Disconnect the radio 

3.  Keep a copy of the full scan, clear the codes and see what comes back.  Sometimes systems will not run if codes are present even when the fault has been fixed.

4.  If you have registered VCDS you can ask it to run some tests by selecting 'Output tests' and         following the prompts on the screen.  It may switch the A/C on during this if it can.  

4.1  Open the A/C controller and look at the live data (measuring blocks).  On a registered version hovering over the various figures should tell you what they should be. 

5.  Have a look and Cent Conv controller under the drivers seat for corroded pins and water damage.  It is worth unwrapping the loom to the controller for inspection also.  Check if you can hear the heater switching to recirc when selecting reverse (have the blower on, it should get louder as you select reverse).

Your CAN codes say 'intermittent' so they may clear and just possibly cause the A/C to come back to life until a fault is detected again.  If they do clear (and only while they stay away) you can ignore them temporarily as the cause of the A/C problem if the A/C still won't work.

Don't forget, fuses first!  Good luck!