Customer FAQs Discover answers to the most frequently asked questions from ADT customers with the click of a button. 1. Why does my keypad display "no ac"? An alarm panel will display “no ac” when the system has lost electrical current. Your system is now operating on backup battery power. The outlet should be checked to verify that it is operational. If the outlet is working properly and your area is not experiencing a blackout or any other power fluctuations, a service call will be needed. Please call our residential or business service number located on our Contact ADT page.