I have a cheaper electrical rate if I agree to pay more between 4PM and 9PM.
So I don't use my AC between 4 and 9. I live in a well insulated (Old but with blown-in insulation over the original.) I try to lower the temperature before 4 PM to keep it from going to high by 9 PM.

• 3 PM It was 103° outside and 72 inside
• At 3 PM I lowered the thermostat to 71
• By 4 it was 73 inside and 105 outside with the AC running conatantly.
• Conclusion The AC cannot lower the inside temperature lower than 30° below the outside.
• I talked to a HVAC technician and he said that was common.
• By 6 PM it was 106 outside and 78 inside
• By 9 PM with the AC off it was 94 outside and 82 inside
• I turned on the AC set to 66 (the hign end of preferred sleeping temperature)
• By 10:30 it was 89 outside and 77 inside
• By 1 AM ut was 83 outsude and 72 inside with the AC running constantly
• By 3AM it was 77 outside and 66 inside