Probably the timer . Do this test: Remove the heavy red wire from the heating element that goes into the timer at a point on the timer marked RH
Then move the timer knob and skirt around while holding a lead to that terminal and any other terminal on the timer. At some point in each cycle their should be continuity. If you can never get a reading between this terminal and any other terminal while repositioning the dial all over then that contact within the timer is burnt and that is why their is no heat. Another theory: somebody did not pay the power bill!