Originally Posted by dobbin
Dryer works on high heat only.
Does not have heat on Auto settings.
Could it be in the timer?
It could be the cycling thermostat. This model uses a bias heater (the two smaller wires) on the thermostat to get lower temperatures.
Whirlpool WP3387134 Dryer Cycling Thermostat - AppliancePartsPros.com
It could be the timer. If you could find the info packet or wiring diagram, that would be helpful for testing the timer.
The way that cycling thermostat works is when a lower temperature is called for, the timer sends power down to the little heater on the cycling thermostat, pre-heating the t-stat so it kicks out sooner. At a lower temp.
If the little heater should burn out or the timer doesn't send voltage to power it, then all temperatures will be "high heat".
Just check across the two smaller terminals on the back of the cycling T-stat. It should have an ohm reading. Watch this video, the important part starts at 7:10.