I have a high mileage (215K) 2004 V70 2.5T which I have owned since new. Recently it has twice shown an ABS warning light and message while driving. At the same time the air conditioner starts blowing warm air, and the temp.gauge, speedo and tach all drop to zero. The fuel gauge still registers, so it is not the whole cluster. The car drives and stops just fine, and when restarted has behaved normally. I'm guessing it is an electrical issue someplace where several circuits join: maybe the ignition switch. Has anyone else had something like this ?

 

The first thing that comes to mind is a momentary power loss and the computer starts shutting down items. The first to go is the AC.

I would start with checking your battery connections (clean them) and then move on to the alternator.