Replacing Defroster Heater – Fix Frost Build-Up in Your Refrigerator
Need the replacement part? Search your model number at for guaranteed fit and fast free shipping.
Understanding the Problem
The defroster heater (defrost element) melts frost that accumulates on the evaporator coils during the refrigerator’s defrost cycle. If the heater fails, frost and ice build up on the evaporator, reducing airflow and cooling efficiency. Over time this causes poor cooling in the fresh food and freezer compartments, longer run times, and water pooling when the ice eventually melts. Before replacing the heater, confirm the fault: check for extensive ice on the evaporator or the freezer back wall, test the heater and defrost thermostat for continuity with a multimeter, and verify the defrost control/timer or main control is advancing into defrost. Often a failed heater is the cause, but a bad thermostat or a defrost control failure can produce the same symptoms—replace only the defective component(s).
Common Symptoms
Excessive frost/ice on evaporator or freezer back wall, reduced cooling/airflow, fridge running almost continuously, water pooling in the drain pan or on the freezer floor.
Common Causes
- Broken/failed defrost heater element (open circuit or shorted to ground)
- Faulty defrost thermostat/bi-metal sensor that prevents the heater from switching on
- Defrost control board or timer failure (no defrost cycle initiated) or defective temperature sensors
Popular Parts That Fix This Problem
These are the most common replacement parts that fix this problem. When you're ready to order, click below to find the right part at PartsDiscount.com — just search by your appliance model number for a guaranteed fit.
Helpful Repair Tip
Unplug the refrigerator, gain access to the evaporator by removing the freezer evaporator cover, and test the heater and defrost thermostat with a multimeter for continuity. An open heater means replacement is required.
Frequently Asked Questions
How do I know the defrost heater is bad?
Check for a thick layer of frost/ice on the evaporator or freezer back wall and poor cooling. With the fridge unplugged and the evaporator cover removed, test the heater with a multimeter for continuity; an open circuit indicates a failed heater. Also test the defrost thermostat—if it’s open when cold it will prevent the heater from turning on. Verify the control board/timer is entering defrost; if the control never triggers defrost, the heater won’t run even if it’s good.
Can I replace the defrost heater myself and how hard is it?
If you’re comfortable unplugging the fridge, removing the evaporator cover, and using basic hand tools and a multimeter, you can replace the heater yourself. Typical steps: unplug unit, remove shelves/drawers, remove evaporator cover, disconnect and remove the old heater, install new heater and thermostat/harness, reassemble. Most jobs take 45–120 minutes depending on model complexity. If the defrost control or board is at fault or wiring is damaged, consider a professional repair.
Real DIY Repair Stories
Be the first to share your repair story!
Share Your Repair Story
Your experience helps other homeowners fix their appliances. Tell us how it went!
Can't Fix It Yourself? Find a Local Technician
It's perfectly okay to call a professional. Some repairs require specialized tools, deep teardowns, or dealing with complex systems that are better left to the pros.
Find the Right Part for Your Appliance
Don't guess — search your exact appliance model number at PartsDiscount.com to find the correct OEM compatible replacement part. They offer fast free shipping, guaranteed fit, and thousands of parts in stock.
Your Free Parts Videos
Whether your dishwasher won't drain, your dryer stopped heating, or your fridge isn't cold, we've created simple repair guides for the most common appliance problems homeowners face. Each guide explains what's going wrong, the most likely causes, and which replacement parts fix the issue. When you're ready to order, we link directly to PartsDiscount.com where you can search by model number and get the right part shipped fast.