The 3977393 dryer thermal cut off fuse is a direct replacement safety fuse used on Whirlpool built electric and gas dryers, most often as the heater box thermal cut off in the 279816 dryer thermostat and fuse kit. It is mounted on the heating element housing and acts as a backup safety device. If the high limit thermostat fails or airflow is blocked, the 3977393 cut off opens at approximately 309 degrees Fahrenheit and permanently kills heater power to prevent a fire.
Key Benefits
-
Restores A Dead Heater Circuit – Fixes dryers that suddenly lose all heat after the heater box overheats
-
OEM Kit Cross Reference – Functions as the cut off half of kit 279816 and matches WP3977393 spec
-
Non Resettable Safety Device – One time open at 309 F, must be replaced after it blows
-
Cheap Insurance Against Fire – Stops the heating element from glowing red inside a lint filled cabinet
-
Fast Back Panel Repair – Two spade terminals, mounts with the existing heater box hardware, 20 to 30 minutes
Technical Specifications
-
Part Number: 3977393 / WP3977393 (cut off half of 279816 kit)
-
Type: Dryer thermal cut off fuse, single use non resettable
-
Trip Temperature: 309 degrees Fahrenheit (154 degrees Celsius)
-
Terminals: Push on spade terminals, fits standard heater box bracket
-
Body Size: Approximately 2 inches long by 1.75 inches wide
-
Material: Ceramic and metal with plastic insulator sleeve
-
Quantity: 1 cut off fuse per order
-
Location: Heating element housing or heater box cover
Compatible Brands
Whirlpool, Kenmore, Maytag, Amana, Roper, KitchenAid, Crosley, Inglis, Estate, Admiral, Magic Chef, Jenn Air
Replaces These Part Numbers
3977393, WP3977393, 279816, 279816VP, 3399848, 2651, AP3094244, PS334299, EAP334299, AH334299, EA334299
Common Symptoms This Part Fixes
-
No heat after the dryer was running hot
-
Heater stopped working but the drum still tumbles
-
Dryer tripped the high limit 3977767 and will not reheat
-
Clothes take two or three cycles to dry
-
Burning smell followed by total heat loss
-
Thermal fuse 3392519 keeps blowing again after replacement
Installation Note
Always unplug the dryer before opening the rear panel. The 3977393 cut off is a symptom, not the root cause. Before powering up, clean the lint screen, transition hose, and exterior vent, check the blower wheel for lint packing, and test the 3977767 high limit thermostat, 3387134 cycling thermostat, and 3392519 thermal fuse with a multimeter. If the heater coil 279838 is grounded or the vent is crushed, the new 3977393 will blow on the first hot load.
Fitment Reminder
This cut off appears in both old style slide on heater box kits and new style 279816 screw mount kits depending on model year. Match your original stamped number or send us the full dryer model tag and we will confirm whether you need 3977393 alone or the full 279816 kit with the L250 high limit thermostat.