Thermal Fuses
With modern design and fire safety issues came the advent of thermal fuses. These very popular fuses are heat sensitive and non-resetting. On all electric dryers, they kill the dryer. Dead!
On a gas dryer a bad thermal, with rare exception, only kills the heat. (One exception is a Samsung gas dryer which kills the motor circuit too.) Usually on gas the dryer still turns. The thermal fuse on the heater box only kills the heat.
Thermal Fuse on Outlet Air Vent
No Power or Bad Door Switch
However, before opening up anything, check for 220vac on an electric dryer and 110VAC on a gas dryer, check the dryer settings and push buttons and operate the door switch. Always try different settings. Is the door switch arm intact and does it feel right? They all click; even the Duet clicks quietly. These checks only take a few minutes.
Comment on the Duet - A bad door switch causes the dryer to emit two beeps. This is the signal that means, "Close the door you dummy."
Duet Door Switch
Broken Belt
Roll the basket; do you feel the motor drag or is the belt broken and the basket is very easy to turn? A broken belt will open the belt check switch and kill a dryer. Belt check switches have appeared in recent years on many designs including the 27" Whirlpools and its clones.
Samsung Belt Check Switch
If the door switch, power, thermal fuses and belt switch are all OK, then you are in for some unusual trouble. It will be necessary to trace the circuit to discover the break. The possibilities are:
1. The push button
2. Timer or computer board
3. Bad Motor