Common fault
Why does frost keep building up in my freezer?
Short answer
If you clear the frost and it returns, the automatic defrost is not finishing its cycle.
The reasoning behind that
Three faults cover nearly every case: a defrost heater that has burned out, a thermistor drifted far enough out of range that it no longer triggers the cycle, or a door gasket letting humid air in faster than the cycle can drive it back out. On built-ins in Mission Hills the gasket is worth checking first. The custom wood panels on these doors are heavy, hinges settle over the years, and a door that no longer pulls itself square lets damp morning air into the cabinet every hour of the day.
How the diagnosis goes
Test the gasket with a dollar bill before you call. Close the door on it at several points around the frame, top, bottom, hinge side and handle side, then pull. It should drag everywhere. If it slides out easily anywhere, and especially near the top of the hinge side where a heavy panel does its damage, the seal is the first thing to deal with and it may well be the only thing.
The moisture is not exotic here. Mission Hills gets the marine layer most mornings for a good part of the year, and these houses are not sealed the way new construction is, so the air going into the cabinet carries more water than the same appliance would see inland. A gasket in good order and a defrost cycle that finishes will handle that. A gasket that has hardened will not, and the ice builds on the coil where you cannot see it long before it shows on the walls where you can.
If that matches what yours is doing, say so when you call — it decides which parts come on the van.
Reviews
What Mission Hills customers say
Scheduled preventive maintenance for our Sub-Zero refrigerator. The technician was thorough, cleaned the coils, checked all seals, and now it runs quieter than ever. Great investment.
Emergency call at 10 PM when our Sub-Zero started leaking water. Technician arrived quickly, found a clogged drain line, and had everything working within an hour. Lifesavers!
We've used them twice now for our built-in Sub-Zero. Both times the service was prompt, professional, and reasonably priced. They're our go-to appliance repair service.
Rated 4.9 from 617 customer reviews.
Appliance down in Mission Hills?
Tell us the brand and what it is doing — we can usually name the likely repair before we arrive.
Questions
Frequently asked questions
The appliance is still under factory warranty. Should I call you or Sub-Zero?
Call the manufacturer first. Sealed-system coverage in particular depends on who performs the work, and there is no sense paying for something you are already covered for. Once the factory warranty has expired, or if the fault sits outside it, we fit factory-approved parts and quote the job before anything is opened. Most equipment in Mission Hills kitchens is well past that date.
What actually happens once the technician is in the kitchen?
Panels come off before any number is quoted. On refrigeration that means the lower grille and the interior panel, checking whether the evaporator is clear or furred with ice, and coil readings by probe rather than off the display. Seals get checked along the hinge side, the drain path traced. Then you hear what is wrong, what it costs, and what leaving it will do.