Freezer defrost

Freezer defrost was not working. I checked contiuity on heater elementand it was good, so i purchased and replaced the defrost thermostat and timer. Now, the defrost element only gets red hot when i rotate the timer to put it in manual defrost. When i put in in the timed defrost mode,the only thing that happens is the condenser fan turns off, but the heater element does not get even warm. What have i missed or am i just lucky and got a bad timer?