Final answer:
Residential air-conditioning systems can have programmable, manual, digital, or no thermostats. Programmable thermostats offer different temperature schedules, while manual thermostats require manual adjustments. Digital thermostats display the temperature digitally and may have Wi-Fi connectivity.
Step-by-step explanation:
In residential air-conditioning systems, the thermostats can be programmable, manual, digital, or none of the above depending on the system. Programmable thermostats allow users to set different temperature schedules throughout the day, while manual thermostats require users to manually adjust the temperature. Digital thermostats display the temperature digitally and may offer additional features like Wi-Fi connectivity. Some systems may not have any thermostat at all, relying on built-in controls.