Noisey A/C when start up Generator

have '96 Fleetwood class C Jamboree Rallye and when starting generator I get a noise coming from the roof top A/C and the generator labors and struggles until I shut the A/C breaker off and generator becomes full power. A/C does fine in cooling but need to keep breaker in off position until needed. The thermostat is in off position when staring generator.
Anyone out there experienced this or know what my problem is??
Kind regards,
Ryder 1100