Why does frost keep building up in my freezer?

What is actually going on

The defrost heater has burned open, the thermistor that calls for the cycle now reads out of range, or the door gasket no longer pulls itself square against the cabinet and is admitting damp air faster than a single cycle can clear. That last one is more common in Del Mar than it is inland, because the air entering the cabinet carries the marine layer with it. Ice on the evaporator then works as insulation, so the number on the display drifts away from what the cabinet is actually holding.

What we check, and in what order

Humidity is the local variable. Every time the door opens on a house near the water, the cabinet takes in air with more moisture in it than the same freezer would see in an inland valley, and all of that moisture has to leave again through the defrost cycle. A defrost system that is marginal rather than broken keeps up in a dry climate and falls behind here. That is why the same model, same age, fails this way more often on the coast, and why a gasket is a genuine repair on a freezer rather than a cosmetic one.

The condenser is involved more often than people expect. A coil loaded with salt and dust rejects heat poorly, so the compressor runs longer to hold the same temperature. Defrost intervals are built around normal run time, and once run time climbs the cycle no longer arrives often enough to clear what has accumulated. The freezer then ices progressively rather than failing outright, which is exactly why owners describe it as getting slowly worse over months instead of breaking on a particular day.

If that matches what yours is doing, say so when you call — it decides which parts come on the van.

Questions

Frequently asked questions