Thanks for all your help.
I have return from my trip, and the generator still not working with the A/C, have send it to the dealer for service will update everyone after I found out what was the problem.
FYI, I have tried all your suggestions:
1 - (Full tank of gas) Turn fridge to LP, water pump off, water heater off .... That make the generator runs for like 15 Min and it still shutting itself off.
2- (Full tank of gas) Turn everything off and just running the Fan.... this time it last 20 to 30 Min but still no luck.
Based on spec 3010ds having a 4Kw generator, it should able to run the A/C (3.5Kw) plus a bit more.