Actually is code 27
It's caused by the alternator on the main engine charging the batteries, and the genset also trying to charge the batteries.
Here is how to overcome it:
Pull the coach over if you are driving, otherwise you are parked with the ISL running, start the genset, then as soon as it try's to pickup the coach load, cancel the charging part of the genset operation. I can do mine in the dashboard Silverleaf system, you may have another way you have to do it. Most likely the inverter panel, just cancel battery charging, then it will allow the back/front a/c's to run just fine.
The main engine through the alternator will charge the batteries while driving down the road.