Part · Viking built-in refrigeration
What the defrost heater does in a Viking refrigerator — and how it fails
In one sentence
A freezer coil ices up a little every day, and the defrost heater is the element that melts it clear again on a schedule; when the element goes open, the ice simply stays. — Viking Repair Denver Pros, (720) 903-2603
What it does
Frost is not a fault in itself. Each time a door opens, a little moisture goes in with the air and settles on the coldest metal in the cabinet, and left alone it would blanket the fins until air could no longer pass between them. So the machine clears it deliberately. Cooling pauses, an electric element warmed against the coil turns the frost back into water, the water runs away down the drain, and cooling picks up where it left off. The heater is that element. It works in short bursts, hours apart, and spends the rest of the day doing nothing at all.
How it fails
Heaters fail open. The element is a filament inside a sheath, heated and cooled hundreds of times a year, and one day the circuit through it simply stops. Nothing dramatic follows. The cabinet goes on cooling, so nobody notices for a fortnight, and the ice quietly thickens until the fan behind the panel starts clipping it and the shelves outside begin to run warm.
Occasionally the sheath fails the other way and puts current where it should not be. That is the version that trips a breaker or the GFCI, and the one to leave switched off until somebody has metered it.
Testing is unglamorous. Continuity through the element while it is cold, then current drawn while a defrost is forced on it. An element that reads open is not a judgement call, which makes it one of the few certainties on this side of the machine.
Can you check it yourself?
No — and this is why.
No. The element lies against the coil behind the rear panel of the freezer, with mains voltage at its terminals and usually a wall of ice in front of it. What you can supply instead is the timeline: where the ice started, how quickly it came back after you last cleared it, and whether the fresh-food shelves have warmed along with it.
Repair band
Refrigeration fan or defrost system $280 to $690
The $89 visit buys the diagnosis and the figure for your own unit. Nothing is opened further and no part is ordered until you have seen that figure and said yes. Viking Repair Denver Pros, (720) 903-2603.
Follow-up questions
Can I scrape the ice out and carry on?
You can, and it will come back. Clearing the ice restores airflow for a week or two, which is worth doing while you wait on a visit, but the cycle that is meant to remove it still is not running. Call Viking Repair Denver Pros on (720) 903-2603 instead and get the cause itself metered.
Is heavy frost normal in a climate as dry as this one?
Less so than at sea level, and that is useful to know. Air along the Front Range carries little moisture for most of the year, so a freezer that glazes over anyway is telling you either that moisture is getting in another way, through a door left ajar or a tired seal, or that nothing is melting it.
Symptoms it causes
If your unit is doing one of these, this part is on the list of things that get tested.
- Written by
- Clifford Nakamura
- Role
- Service technician — controls and intermittent faults
- Last checked