Clogged dryer vent can cause fuse damage. 3977393 Tthermal cut-off switch safety assembly is 309F, Compatible if your existing fuse is 325F. 3977767 Cycling Thermostat- It acts as as safety mechanism that keeps the dryer from overheating. the dryer temperature reaches 221 degrees Farenheit, this piece will shut down power to the heating until it by 80 degrees Farenheit.