[Dave V]

My dryer only runs at full hot, even when set to low heat. It will run at fluff with no heat at all though. The vent is clear.

[denman]

Could not find a wiring schematic but you should have one
The dryer has a cycling thermostat, this device not only monitors the dryer temp it has an internal heater so it switches on/off at a lower temp
This is probably shot, either the contacts are welded together or the internal heater is open. Can be checked with an ohm meter.
Could also be your temp select switch but this is less likely

Search the model at PartSelect to locate for a parts breakdown of the dryer

Perhaps another person can provide more info on the wiring