Another thing to remember is the humidity levels. During this period, dendrobiums do not need a lot of moisture. Very little water will be enough to keep their roots alive. Also keep in mind that their roots constantly need plenty of air circulation so you should place them where there is a lot of fresh air.
Remember, that is based on energy usage, not comfort-levels, which are the purpose of having an air conditioner, in my not-so-humble opinion. Fact: At night, the ideal temperature comfort range for Americans drops to 65 to 72 degrees Fahrenheit (or about 87 degrees if you are my wife).
For almost any automotive air conditioner, the air at full blast should be around 40F. Use a regular thermometer for a more accurate diagnostic. On the ride home today the AC doesn't seem to be cooling well, temperature outside was about 80. I checked the vents with my IR gun when I got home I get about 56-57.