The induced fan comes on then the burner comes on for about 90 seconds then shuts off without the main blower coming on. The induced fan continues to run then the burner comes on again for 90 seconds of so then off again with induced fan still running. Finally 15 minuites later the blower starts while the burner is off. After a couple minuites of this the burners does come on for a short peroid of time and off then back on until finally the thermostat is satiefied and the unit shuts down.