Frost and ice · Denver
Why is there frost on the back wall of my freezer?
The short answer
Frost builds on the rear panel when moist air keeps reaching the evaporator behind it, or when the defrost cycle stops clearing what collects. Sub-Zero Appliance Repair Denver measures the defrost circuit and proves the drain before anything is replaced — (303) 729-0972.
$89 service call, credited against the repair.
Before you call
- Look along the whole gasket, top corners included, for a split, a flattened run or a patch of dry rot.
- Check nothing is holding the drawer or door off its seal — a bag, a box lid, a basket sitting proud.
- Read the freezer setting on the control panel; the manufacturer's own answer pages ask for 0°F.
- Pull the lower grille and look at the condenser: matted dust there makes the system run in longer stretches.
Stop here and call Sub-Zero Appliance Repair Denver on (303) 729-0972 if the sheet is back within days of a full defrost, or the drawer has stopped closing against it.
What it usually turns out to be
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A defrost element that has failed
Ice arrives as a clear sheet, thickest high on the panel, and it grows back on the same rhythm every time.
Defrost heater, thermostat or sensor$280–$680
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A gasket letting room air in
The frost is softer and furrier, worst near the front edge where the warm air arrives, and the seal shows a split or a flattened stretch.
Door gasket or seal replacement$260–$700
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A frozen drain tube
Meltwater never leaves, so it refreezes where it stands and the floor of the compartment ices up alongside the panel.
Quoted after the diagnosis
When it is worth a visit
Book the visit once the ice returns on a schedule, once a drawer or door will not close against it, or once the compartment is sitting well above zero. Those three say the fault is in the defrost circuit or the drain rather than in how the freezer is being used.
There is a longer version of this one in the guides: read it through.
Where on the panel it sits
Ice that is thickest at the top of the rear panel and thins downwards has been made and re-frozen in place. Ice that is even, soft and worst by the door has blown in from the kitchen. The first points at the defrost circuit, the second at the seal, and the two are fixed by completely different parts.
Follow-up questions
Is any frost in a freezer normal?
A light bloom on the walls after the door has been open a while is ordinary, and the manufacturer says so. What is not ordinary is a hard sheet across the rear panel that survives the door being left shut for a day or two.
Should I chip the sheet off myself?
No. The panel goes brittle at freezer temperature and the tubing behind it is soft aluminium, so a screwdriver or a blade turns a small job into a sealed-system one. Warm the room, not the ice: everything out, the section switched off, towels down, door open.
What does the visit actually establish?
Whether the defrost circuit is working and whether the drain is clear, both measured rather than assumed. Sub-Zero Appliance Repair Denver puts a reading on the heater and the sensor and runs water through the drain path, and the $89 diagnosis comes off the repair you approve.
Talk to someone
Still doing it after the checks?
Say what changed and in what order, and the technician packs for that fault rather than for a guess. Technicians work 8:00 am to 8:00 pm, any day of the week, and the line takes a call 24/7.