5500VA is around 47+ amps at 115 vac
Motors including A/C compressors have around a 0.96 Power Factor
You have enough generator for two A/C units
The problem is the Intellitec load shedding power management, the current transformer sensor, is on the power input hot line to the Main Breaker for your panel, the Intellitec system is set for 30 amps for the shore cord input to prevent overload,
On my MH , a 1997 Bounder there is an extra circuit breaker in the service panel, to put one A/C on the second winding from the 5500 Onan, and avoid having both units on the "measured" hot wire of winding number 1 that's feeds the main breaker
Some RVs (example 1992 Komfort 31ft) come with an extra 120v switch , for switching one of the a/C's between shore and generator, in my case here in the Bounder, that's the extra circuit breaker wiring
Do you have either of these in your RV, check to see if it's in the correct position for generator use
If not
There is an extra load turned on
Front a)c has problems
Your two batteries are drawing more charge than you think, to check turn off or unplug converter,
Or charge batteries 30 minutes before turning on the a/c units
I can explain it to you.
But I Can Not understand it for you !
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Connected using T-Mobile Home internet and Visible Phone service
1997 F53 Bounder 36s