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.