Mello Mike is on the right track I think. When Terry (overlander63) came over to do our A/C install, his had a similar problem because the generator wasn't supplying enough power at only 108 volts. If it's a generator you need one that has a dedicated 30 amp that's not split with the other plugs to share the power. Or if on house power then also a 30 amp dedicated breaker. These things seem to need their own power source with a 30 amp circuit. So needless to say we went out a got a new generator at Costco. It's a Champion 7000/6000 model 40030. It actually has 2 dedicated outlets for 30 amps each with their own breakers, both twistlock, on 3 prong, and one 4 prong type. It also has an additional 4 outlets that share 20 amp breakers (2-20 amp). It was $649. We don't intend on hauling it with to camp with, just to use at home for the AS and for emergency power outages to keep the appliances/lights on. Running a dedicated line from our house power panel was not an option for us. Did you install the A/C yourself, or have it installed? If you had it installed somewhere I'd go and check with them about trouble shooting if the power theory doesn't check out. Hope this helps.
Good luck.
Mary