A Sub-Zero has two filters, and they live on completely different clocks. The water filter gets the attention — it has a dispenser that slows down and ice that tastes off. The air purification cartridge just sits in its housing, quietly scrubbing the air inside the fridge every 20 minutes, and it gives you almost no drama when it runs out. It simply stops keeping up.

That cartridge is the 7042798, and it is the reason a Sub-Zero keeps strawberries alive into the second week. When it fades, the fridge still feels cold — but the food tells the truth first.

What the 7042798 actually does

This is not a water filter and it does not work like one. It is an activated-carbon air purification cartridge built on technology Sub-Zero describes as NASA-based, and it works on the air, not the water:

Ethylene gas — the ripening compound fruit gives off. Scrubbing it is what slows the whole produce drawer from ripening in lockstep.
Mold spores, viruses and bacteria — the airborne load that seeds spoilage.
Odors — onion, garlic and fish smells that otherwise migrate into butter, milk and last night’s leftovers.

The cartridge cycles the fridge’s air roughly every 20 minutes, which is why a fresh one makes a mixed fridge smell like nothing at all.

Why it lasts a year (when water filters last six months)

Air is a lighter workload than water. A water cartridge pushes every glass and ice cube through carbon block; the air cartridge only has to handle the gases and spores in a sealed box. Sub-Zero rates the 7042798 for 12 months — twice the life of the fridge’s water filter — which is exactly why it gets forgotten: by the time it is due, most owners have changed the water filter twice and never once thought about the air side.

The signs yours is done

There is no taste test for air, so judge it by the food:

Produce fades faster than it used to — berries softening or molding days earlier than they did when the fridge was newer.
Smells mingle — yesterday’s curry in today’s milk, onion in the butter.
The calendar says so — if it has been 12 months, it is done whether or not you can smell a difference; the carbon exhausts on schedule, not on symptoms.
You cannot remember ever changing it — the most common sign of all.

Our comparison of refrigerator air filters (the Frigidaire PureAir family) covers the same signs for other brands: https://discountedfilterstore.com/frigidaire-air-filters-compared/ — the Sub-Zero simply runs on a 12-month clock instead of a 6-month one.

How to replace it (about two minutes, no tools)

Find the air purification housing inside the fridge (check your manual if it is not obvious — placement varies by series).
Remove the old cartridge.
If the new cartridge has a light dusting of carbon on its surface, wipe it with a paper towel first — that is loose carbon from shipping, it is normal, and the product page says so.
Place the new cartridge in the housing.
Write the date on the cartridge or set a 12-month phone reminder — our 6-month reminder system adapts to a yearly cycle just as easily.

The genuine OEM cartridge is here: https://discountedfilterstore.com/shop/sub-zero-7042798-air-filter-cartridge/ — $29.99 for a single, with multi-packs up to 4, and free US shipping on any amount.

7042798 or 7007067?

Same cartridge. Part number 7042798 replaced 7007067; they are the same unit and fit the same refrigerators (you may also see it listed as SUB-7042798, AP6036325 or PS11769979). If your manual or your old cartridge says 7007067, the 7042798 is the correct current replacement — order it without a second thought.

One limit, stated plainly: the cartridge only fits Sub-Zero units that HAVE a built-in air purification system. If your model has no housing for it, there is nothing to replace — check the manual before ordering, or contact us with your model number and we will confirm.