The Whirlpool WP3398128 Cycling Thermostat regulates dryer temperature by switching the heating system on and off as the selected temperature range is reached. This replacement component monitors heat inside compatible dryers and responds to temperature changes to maintain the intended drying range. Proper thermostat function supports consistent heating and reduces excessive temperature fluctuations during drying cycles. A faulty thermostat may cause overheating, insufficient heat, or inconsistent drying results. Replacing a damaged thermostat can restore temperature regulation and support normal dryer heating.