A: Many cigar smokers encounter this same problem every year, too. First, I would NOT replenish the humidifier. In other words, let it get down to about 65% and try to keep it there. If the readings, as you say, have already climbed up to the 70% range, remove the humidifier and keep it out for a half a day or so. Keep it in a ziploc bag until the RH in your humidor dips below 64%. After 24 hrs, put the humidifier back in the humidor and take a reading . Repeat this procedure until you can stabilize the RH at around 65%. The cigars should settle nicely under those conditions.
As far as the air conditioning is concerned, moving the humidor closer to the AC would be a plus. I would try that first, before doing the above.
Re Cigar Oasis: Yes, they all monitor humidity and temperature. Note the XL unit (shown above) is made for humidor that holds at least 50-300 cigars. For 75 you want to go with the Cigar Oasis ULTRA model. 100 and higher, see the other XL models.