I purchased a new Champion 4000 watt generator a few months ago and tested it out after about 30 minutes of run time and it ran my 15k air with no apparent problems. I'm planning on going to the Nascar race at the Texas Motor Speedway at the end of the month so I got my Genny out for another test, and hooked it up, ran it about 30 minutes and kicked on the air and it seemed to be ok. Then, I noticed my voltage indicator needle inside the trailer was varying back and forth between 115v to 125v . Listening to the compressor motor it sounded like it was humming in the same rythm of the needle movement. Is this normal, or do I have a voltage regulator problem on the Generator? Secondly, will it hurt my AC for the voltage to vary back and forth like that? Without the air on I tried the Microwave and the voltage went to a steady 130v. Any input will be appreciated. I know to contact Champion but thought I would throw it by you guys first.