Common fault
Why does frost keep building up in my freezer?
Short answer
Frost that comes back after you clear it means the automatic defrost cycle is starting but not finishing. Three things account for nearly all of it: the defrost heater has failed, the thermistor that triggers and ends the cycle has drifted out of range, or a door gasket has lost its magnetic pull and is admitting humid air faster than the cycle can remove it. Once the evaporator is furred with ice it insulates itself, so the compartment degrades a little further every week rather than failing outright. That is why owners describe this one as getting gradually worse.
Humidity is why this fault presents earlier and harder in La Jolla than it would inland, and why we take it seriously when a customer says the frost is back. Through the long run of gray coastal mornings that this town gets from late spring into summer, kitchens near the water sit at high relative humidity for most of the day, and plenty of houses on the ocean side run open to the air rather than air conditioned. Every door opening admits that moisture, and it condenses on the coldest metal available. A defrost cycle in good order handles it. A cycle running on a drifted thermistor handles most of it and leaves a little behind, and the little that is left is cumulative.
Clearing the frost by hand is worth doing to protect the contents, but understand that it tells you nothing diagnostically and buys weeks rather than a fix. What we do instead is force a defrost cycle and watch it: heater drawing current or not, ice actually clearing or not, thermistor resistance checked against its curve at a known temperature. That sequence separates the three causes definitively, and it takes less time than guessing. If the heater and sensor both check out, the answer is the door, and on Sub-Zero units with heavy custom panels a door that has dropped out of square is a routine finding rather than an unusual one.
If that matches what your appliance is doing, say so when you call — it tells us which parts to bring, and most of these are finished in one visit.
Reviews
Our Sub-Zero freezer went out on a Sunday. They answered immediately and had a technician at our home in Bird Rock within two hours. Incredibly professional and fast service!
- ★★★★★
The technician who fixed our wine cooler was so knowledgeable. He explained the problem clearly and gave us a fair price. Excellent service for our home near La Jolla Shores.
- ★★★★★
Finally, a repair service that operates 24/7 as advertised. They were able to come late in the evening to fix our refrigerator in the Muirlands area. Lifesavers!
Appliance down in La Jolla?
Tell us the brand and what it is doing — we can usually name the likely repair before we arrive.