Sub-Zero Water and Air Filters: When to Change Them and How to Clear the Reminder

Two filters that have nothing to do with each other

Almost every confused search on this subject comes from the same place: people assume there is one filter, and there are two. They sit in different places, do different jobs, run on different schedules, and are reset differently.

The water filter treats the water going to the dispenser and the ice maker. It is a physical cartridge that water passes through, and it is the one that affects how your ice and water taste.

The air purification cartridge sits inside the refrigerator compartment and treats the air. It reduces odors and deals with ethylene gas — the gas fruit gives off as it ripens, which makes everything else near it ripen faster.

Neither one affects the other.

Changing the water filter does not clear the air cartridge reminder, and a new air cartridge does not improve the water. Half the "I changed the filter and the light is still on" calls are somebody having changed the other one.

When each is actually due

Filter	Interval	What tells you
Water filter	About every 6 months	Indicator, or reduced flow, or taste
Air purification cartridge	About every 12 months	Indicator, or odors that will not go

Changing the water filter

Where it is depends on the model. On many built-ins it is inside the refrigerator compartment, usually toward the top; on others it is behind the grille above the doors. The manual for your model says which, and once you have found it the first time you will not lose it again.

1. Have the new filter open and ready. There will be some water.
2. Have a towel underneath. A cupful is normal.
3. Remove the old cartridge. Most turn a quarter turn and pull out; some release with a push. Never force it — if it is not moving the way you expect, check the direction rather than applying more effort.
4. Fit the new one the same way, until it seats and locks.
5. Flush it. Run about two to three gallons through the dispenser, or discard the first two or three batches of ice. New carbon filters shed harmless fines and trapped air, which is why the first water is often cloudy or tastes of nothing much. This step is skipped constantly and it is the reason people conclude a new filter has made things worse.
6. Reset the indicator from the control panel.

Changing the air purification cartridge

Simpler, and mostly a matter of remembering it exists.

1. Find it inside the refrigerator compartment — the manual for your model gives the position.
2. Release the cover, take out the old cartridge, fit the new one.
3. Reset the indicator from the control panel.

Once a year, and it is worth doing even when nothing smells: by the time an air cartridge announces itself, it has been doing nothing for a while.

Resetting the indicator

Both reminders are cleared from the control panel, and the key sequence differs by series.

We are not going to print a universal one here. A confidently wrong button combination in a guide is worse than no guide, and these units differ enough between generations that any single answer would be wrong for somebody. The sequence is in the use and care manual for your model, in the section on the display or on service reminders.

If you do not have the manual: tell us the model number and we will tell you the sequence for it. That is a phone call, not a visit, and we would rather answer it than have somebody hold buttons at random on a control panel.

What South Florida does to the water side

When the light comes back too soon

A reminder that reappears weeks after a change means one of four things, in order of likelihood:

1. It was never reset, and it is simply continuing an old count.
2. The wrong reminder was reset — the air cartridge cleared instead of the water filter, or the other way round.
3. The reset did not take. Some sequences need the button held for longer than feels natural.
4. There is a genuine problem with the control, which is rare and diagnosable.

Work down that list in order. Three of the four cost nothing.

When it is not the filter

The filter gets blamed for a lot of things it did not do. Worth ruling out before spending money:

• No water at the dispenser at all. More often a frozen supply line or a fill valve than a filter — a clogged filter reduces flow, it rarely stops it dead.
• Ice tastes of the freezer. That is odor absorption in the compartment, which is the air cartridge's job, or food stored uncovered. See ice or water tastes off.
• Cloudy ice. Usually dissolved air and minerals in the supply, not the filter.
• Very slow ice production. Water pressure, a partially frozen line, or the ice maker itself rather than the filter. See ice maker not making ice.

If you have changed the filter, flushed it properly, reset the indicator and the problem is still there, it was not the filter. Tell us the model number and what the water or ice is actually doing, and we will tell you what it usually turns out to be before anybody is dispatched.