My AC is not working well. It's cold for a few seconds and then room temp for a minute or so and then cold for a few seconds. The system is charged and it fades in and out at all settings. Does a temp sensor control how long the cold air is allowed to run as well as how cold it is?
It sounds like you have moisture in your system. Moisture causes ice to form where the expansion valve discharges into the evaporator. When enough ice forms, it prevents the flow of refrigerant and the evaporator will begin to warm. The ice melts and allows the flow of refrigerant to cool the evaporator and the ice begins to form again. The fix is to reclaim the refrigerant, replace the drier, evacuate and recharge the system. This is more likely the case if you've had the system open for any reason.