When an air conditioner turns off, it stops actively cooling the air, and its compressor ceases to run. So, immediately after the air conditioner turns off, the cooling effect stops, and the temperature inside the house will begin to rise gradually as the heat from various sources, such as appliances, lights, and occupants, starts to warm up the air.
However, the extent to which the inside of your house will get warmer depends on several factors, including:
Insulation: The level of insulation in your home plays a significant role in how quickly the indoor temperature rises after the air conditioner turns off. Good insulation helps to retain the cooled air for a longer period, slowing down the heat transfer from outside.
Outdoor Temperature: The outdoor temperature at night also influences how fast the indoor temperature will rise. If it's a cooler night, the temperature increase inside the house will be slower compared to a hot and humid night.
Indoor Heat Sources: If there are appliances, electronics, or lights running, they generate heat, which will impact the indoor temperature.
Size and Efficiency of the AC: A larger and more efficient air conditioner can cool the house more effectively and maintain a cooler temperature for longer even after it turns off.
So, while the air conditioner doesn't actively make the inside of your house colder once it turns off, it does create a temporary cooling effect during operation, and the indoor temperature will gradually rise after it's turned off, depending on the factors mentioned above. If you want to maintain a cooler indoor temperature during the night, you may need to adjust your thermostat settings or consider using fans or natural ventilation to help circulate and cool the air.