It seems that my A/C is oversized based upon my observations of how the system has been operating. I've been timing the runtimes in the afternoon when I had the opportunity over the past two weeks. I have a Honeywell RTH7500 thermostat set at 75*F. When the outside temperature is at or a few degrees above the outside design temperature of 92*F, I get a runtime of ~15 min. and an off time of ~5min. I did manage to catch one of the +100*F days and the runtime was ~20min with an off time 5min.
When it comes to humidity, I am lucky if I see anything less than 60% RH. Right now I am blaming my short runtimes for the high humidity. I have seen a number of people on here post their RH at something substantially less than 50%. Is it possible to hit these low RH numbers in areas with hot humid summers without supplemental dehumidification and a properly sized A/C unit?