The heat is another important function of a dryer. Many current dryer models have a 'one-time', non-resettable, thermal fuse or safety. These safety devices will open should the dryer's vent not be installed properly, or if it becomes restricted. Once this happens, the dryer will no longer heat and will require the part to be replaced to correct the condition. On some dryer designs (usually gas) failure of one of these thermal fuses will totally stop the dryer operation altogether.
On older models without one of these thermal safeties, poor venting can cause the dryer to cycle on its safety thermostat, instead of the temperature control thermostat. This usually contributes to poor drying and can cause overheating. On some models, the malfunctioning of the timer operation affects some cycles.
