The smoke alarm should be operating once AC power is applied or fresh batteries are installed, and testing is complete.
You can test your smoke alarm by pushing the Test/Hush button on the cover and holding it down for a minimum of 5 seconds. This will sound the alarm if the electronic circuitry, horn and battery are working. In an interconnected installation, all interconnected alarms should sound when the test feature on any one of the interconnected alarms is activated. If no alarm sounds, check the fuse or circuit breaker supplying power to the alarm circuit. If the alarm still does not sound, the unit may have defective batteries or another failure.
DO NOT use an open flame to test your smoke alarm! You could damage your alarm or ignite combustible materials and start a structure fire. Test your smoke alarms weekly to ensure proper operation. Erratic or low sounds coming from your smoke alarm may indicate a defective alarm, and should be returned for service (refer to your warranty).