Newbie-type question about power supply at home

Update (and a question) -- using a heavy duty extension cord and all of the tips above, I tested the voltage in the trailer, which was 119.5. And then I ran the air conditioner, and the voltage is 117.

Not perfect, but it works!!

So of course the follow-up question -- if I run the a/c at 117 volts for a long time, will that harm any of the components in the a/c system? I know that when running the a/c, I will not run any other major appliance (like the furnace or the toaster).

Thanks, as always!