This is a “low cranking speed sense” fault. The fault can be caused by numerous things, low starting battery voltage, bad or loose connections, and several others that would be difficult to check on the road.
Make sure your batteries have a good charge, if they do then check the connections on the generator to see that they are clean and tight. If those don’t fix the problem then you need to go to an Onan Service center.
If you can’t get the generator working you can try hanging a blanket or something similar behind the front seats to keep the cool air from the dash contained to the front.
Best of luck, wish I could be more help.
Dave & Myra
One day your life will flash before your eyes,
make sure it's worth watching!