Most air conditioning units usually have built-in mechanisms that automatically shut off the system if the desired temperature is already met. Whenever there are problems that allow the A/C unit to continue operating without turning off, its owner must have the air conditioning unit checked. Usually, at least one of the three components have problems if this situation happens.
The Thermostat is Broken
The thermostat sets the temperature the A/C need to cool the room. If the desired temperature is reached, the thermostat sends signals to the rest of A/C to automatically shut off the system. An air conditioning unit with a broken thermostat may continue cooling the room or house beyond the set temperature. Repairing or replacing the thermostat may fix the unit.
The Contactor is Broken
The contactor is the system that shuts off the A/C unit. The thermostat usually sends its signals to the contactor first to shut off the entire system once the area is cool enough. Depending on the usage of the A/C unit, the contactor can either wear down or break. Replacement is usually the solution for this.
The Duct is Clogged
Another possibility for an A/C to not turn off is if the set temperature is not being met. A clogged air duct or dirty filter should be cleaned accordingly so that the A/C can cool properly.