Every year in the hot weather, I have a conversation with my wife that goes something like this:
- Me: Dear, could you not set the AC units so low when none of us are in the room? It wastes energy.
- She: But it's hot, and I want it to cool down quickly.
- Me: Yes, dear, I know, but turning down the temperature set point doesn't make it cool off any faster.
- She: Well, it should.
The vast majority (if not all) of air conditioners (and refrigerators, dehumidifiers, etc.) have two settings: a fan setting and a temperature setpoint. The fan setting just controls how hard it blows. The temperature setpoint does not control the temperature of the air the unit puts out. Instead, it controls when the system goes from full run mode to idling mode.
AC units push out only one temperature of cold air: cold. They work until their temperature sensor shows a temperature lower than their setpoint, and then they go idle (although their fans may continue to blow). When the temperature at the sensor rises above the setpoint again, it turns the system back on.
Turning the setpoint down very low will not make the room cool down any faster; it will simply make the AC unit work longer and not go idle as soon.