I think our coach shuts down its landline at 102 volts to protect itself. Personally I go into concerned and watchful mode when I read 107 volts on either leg. In that voltage neighborhood I don't like running an AC, and will usually take my meter to the power pedestal to start ferreting out any voltage drop cause, and/or advise the park management. Certainly, I am at ease at the ideal 119-120 v.
AC pulls max current at startup, like most motors, and if the voltage pressure isn't there to push it the unit will overwork trying to get up to full op. The result is overheating and a costly failure. As you may know, a hot day in a full older park can stress resources such that any one site's voltage can be below snuff.
Joel