Part · refrigerators · auto-defrost
Lynnwood defrost heater repair for a frosted-over freezer coil
Freezer still cold, fresh-food side drifting warm, and white frost creeping across the freezer’s back wall? That pattern usually means the defrost heater has quit.
- $85 diagnostic, counted inside the repair price you approve
- One written price before any part is replaced
- Monday through Saturday, same-day when the morning allows
- MachinesEvery auto-defrost refrigerator and upright freezer
- Main clueEven frost coating the whole evaporator coil
- Test usedContinuity and resistance across the heater terminals
- Owner checkLook for frost on the freezer’s rear wall
Defrost heater
What the defrost heater does behind the freezer wall
In Lynnwood homes we confirm it with a meter before replacing anything.
Every auto-defrost refrigerator hides its cold coil, the evaporator, behind a cover at the back or bottom of the freezer. Each time a door opens, moist kitchen air drifts in, and that moisture freezes onto the coil’s thin fins. Left alone, the frost would keep growing until air could no longer pass through. So every so often, on a timer or on an adaptive control that counts door openings and run time, cooling pauses and power goes to the defrost heater: a metal-sheathed rod, a glass tube or a foil strip pressed against the coil. It warms the fins just enough to melt the frost. The water runs down a trough, through a drain tube and into a pan under the cabinet, and a small thermostat ends the heat once the coil is clear.
Defrost heaters wear out from repetition. Years of heating and chilling stress the element until it opens, much like a burned-out bulb filament. Glass-tube heaters also crack when someone chips at the ice with a knife, or when moisture works past the end caps. A dead heater is only half the story, though. A gasket that no longer seals, a door that sags, or a freezer packed so full the door rests ajar loads the coil with far more frost than any heater was built to clear. A clogged drain tube refreezes the melt water into a block at the base of the coil. The defrost thermostat or the control board can also fail and leave a sound heater idle, so we test the whole circuit before naming a part.
Signs
Signs the defrost system has stopped keeping up
- The freezer still feels cold, but milk and leftovers in the fresh-food section keep getting warmer.
- A thick, even layer of frost shows on the freezer’s back wall or around its air vents.
- Unplugging the refrigerator for a day fixes it for a week or two, then the warming returns.
- A scraping or rattling noise from the freezer as the fan blade brushes against built-up ice.
- Water collects under the crisper drawers, or a sheet of ice forms on the freezer floor.
- The vent feeding the fresh-food side blows weak, barely cool air even on the coldest setting.
Where we find it
Where we replace defrost heaters most often
| Refrigerator or model type | What we see with the defrost heater there |
|---|---|
| Side-by-side refrigerators | Tall coil behind the freezer wall; frost chokes the duct to the fresh-food side. |
| Bottom-freezer and French-door models | Coil under the freezer floor or at its back; ice in the drain trough is common. |
| Top-freezer refrigerators | Simple timer-driven defrost, where heater, thermostat and timer all wear with age. |
| Garage refrigerators and upright freezers | Damp garage air loads the coil with frost, so door seals matter most. |
How we test it
How our technician confirms a failed defrost heater
- 1
Read the frost pattern
With the evaporator cover off, the technician studies the coil. Frost spread evenly over every fin points to a defrost failure. Frost on only the first few passes of tubing tells a different story, one about the sealed system, and we explain that finding in plain words.
- 2
Meter across the heater
Power off, the heater leads come off and the meter goes across the terminals. An open reading means the element has broken inside. A reading that matches the rating on the model’s tech sheet clears the heater and moves the search further along the circuit.
- 3
Check the defrost thermostat
The bimetal thermostat clipped to the coil should read closed while it is frozen and open once it warms. One that stays open on an iced coil blocks power to a perfectly good heater, so it gets its own continuity test before any part is chosen.
- 4
Force a defrost cycle
Most controls have a service mode, and older timers can be advanced by hand. The technician starts a defrost, clamps an ammeter on the heater circuit to confirm current is flowing, and watches the frost begin to soften before the cover goes back on.
Booking
Book a refrigerator visit
Tell us the machine and what it is doing, then where to come. We call back to set a two-hour window, Monday through Saturday.
- $85 diagnostic counted inside the repair price once you approve it
- Up to $15 off your first repair with us — tick the box
- $10 off the diagnostic of a second appliance on the same visit
Prefer to talk? (425) 905-3879 · Mon–Sat 8 a.m.–7 p.m. · Sunday closed
Puget Sound angle
Damp air, garage fridges and frost in Puget Sound homes
Marine air carries moisture most of the year, and every door opening hands some of it to the evaporator coil. In Lynnwood kitchens from the 1960s and 70s, tired gaskets add a steady trickle. Garage units have it harder. During the June 2021 heat dome, with unofficial readings of 109°F in Lynnwood, many ran without a break, and a coil that never rests builds frost faster than a weak heater can melt it. Outages like the November 2024 windstorm, which left more than 70,000 Snohomish County PUD customers dark at its peak, can let frost melt partway and then refreeze as a solid block when power comes back. We check for sweating gaskets on every defrost call.
FAQ
Defrost heater questions
Can I defrost the freezer myself while I wait for a visit?
Yes, and it is a safe stopgap. Move food to a cooler, unplug the refrigerator, prop both doors open and lay towels on the floor. Once the coil has fully thawed, often by the next day, plug it back in. If cooling returns and then fades again over a week or two, the defrost system is the likely cause, and that history helps our diagnosis.
Is a frosted coil always the heater’s fault?
No. The defrost thermostat, the timer or the main control board can each keep the heater from getting power, and a blocked drain tube builds ice that looks like a heater failure. We test each piece of the circuit, then name the one that failed. Replacing the heater alone when the thermostat is at fault only brings the frost back.
How long does a defrost heater repair take?
When the heater for your model is on the van, the repair usually happens during the same visit, once the coil is thawed enough to work on. Heavy ice takes a while to clear with steam or warm air, so plan on keeping frozen food in a cooler. A heater that has to be ordered means a return trip, and that second trip carries no added charge.
My refrigerator is old. Is a new heater worth it?
Often it is, since the heater is a modest part next to the cabinet, compressor and sealed system around it. The technician also tells you what else the meter showed, such as a compressor running hot or a coil frosting only partway, so the written price sits beside the full picture. You decide with all of that in front of you.
Do you handle defrost problems in Edmonds and Mill Creek too?
Yes. We cover Lynnwood, Edmonds, Mountlake Terrace, Brier, Mill Creek and Mukilteo, and the defrost diagnosis runs the same way in each. Garage refrigerators in Mill Creek and older kitchen units in Edmonds hillside homes are both familiar calls. Book online or phone us, and we call back to set a two-hour arrival window.
Book the $85 diagnostic visit
The $85 diagnostic pays for finding why the coil frosted over; say yes to the defrost repair and that amount becomes part of the one written price, say no and it is all you pay.