Jandy AquaPure Salt Cell Check System Fault Tree

Why this matters

The Jandy AquaPure salt chlorinator's "Check System" indication (paired with one or more lit fault LEDs: Check Cell, Service Cell, No Flow, low/high salt, or temperature) is a catch-all that stops chlorine production until you read which condition tripped it. Owners often see only the alarm and assume the cell is dead, then pay for a cell that was fine. The fault is a decision point with several distinct causes (flow, salinity, temperature, cell life, and wiring) that each have a different fix. Walking the AquaPure's own LED logic in order turns a vague "Check System" into a specific, confirmable root cause and keeps you from condemning a healthy cell or, worse, leaving the pool unsanitized.

Symptom presentation

The AquaPure power center shows Check System with one or more status LEDs lit. Common pairings: Check Cell or Service Cell (cell-related), No Flow / flow LED (water movement), low-salt or high-salt indication (salinity), or a temperature lockout in cold water. Chlorine output is suspended. The pool may read zero free chlorine over several days. The cell may have high lifetime hours, visible scale, or a worn coating; or the install may have a flow-switch or wiring issue unrelated to the cell itself.

Quick checks

• Read exactly which LEDs are lit alongside Check System. The specific LED is the fault; "Check System" alone is not the diagnosis, so do not condemn the cell on the headline alarm.
• Confirm the pump is running and flow is established; the AquaPure suspends production with No Flow and will not make chlorine on low flow. Verify the pump runtime actually covers the chlorination schedule the controller expects.
• Check displayed salinity against a bench salt test. Low or high salt locks out production; verify the true value with a K-1766 titration or calibrated meter before adding salt, because the cell can misreport salinity when scaled.
• Inspect the cell for scale and coating wear, and note lifetime hours; AquaPure cells have a finite plate-coating life and degrade gradually toward a Service Cell fault.
• Check water temperature; cold water below the cell's operating floor triggers a temperature lockout that is normal seasonal behavior, not a failure, and resumes on its own.
• Inspect the cell cable connector at the power center for corrosion or a loose lock; an intermittent connection mimics a dead cell and throws cell faults that come and go.

Isolation tree

1. Is the No Flow / flow LED lit? If yes, the unit sees inadequate flow. Verify pump running, baskets clean, valves open, and the flow switch wiring/operation. Restore flow; if the flow switch is faulted, service it. If flow is proven good, continue.
2. Is a salt LED (low or high) lit? Compare the display to a bench salt test. If true salt is genuinely low, add pool-grade salt to the AquaPure target and run a turnover. If the display reads low but bench salt is in range, the cell may be scaled or worn (it senses salinity), continue to step 4. If salt is truly high, dilute. If salt is fine, continue.
3. Is the temperature LED / cold lockout indicated and water is cold? That is protective, not a failure; production resumes when water warms. If temperature is normal, continue.
4. Is Check Cell or Service Cell lit? Inspect and clean the cell of scale per OEM (dilute-acid soak), and re-seat the cell electrical connector. After cleaning, does the fault clear and output return? If yes, scale/connection was the cause. If it persists, continue.
5. Cell connector and band: inspect the cell cable, the power-center connector pins, and grounding. Corroded or loose contacts mimic a dead cell. Repair and re-check. If wiring is sound, continue.
6. With flow, salt, temperature, scale, and wiring all good, a Check/Service Cell that persists on a high-hours cell means the cell coating is depleted. Replace the cell with the correct AquaPure model.

Confirming diagnosis

Confirm against the specific lit LED, not the generic alarm. Flow is confirmed when restoring flow or repairing the flow switch clears the No Flow LED and production resumes. Salinity is confirmed by a bench salt test agreeing with corrective action. A scaled cell is confirmed when an acid soak restores output. End-of-life is confirmed when a clean, well-connected, adequately-flowed and salted cell with high hours still shows Check/Service Cell and produces little or no chlorine, and a new cell clears it. Verify recovery by confirming free chlorine production after the fix, not just a cleared LED.

Remediation

• No Flow: clean baskets, open valves, ensure pump runtime covers a turnover, and repair or replace a faulted flow switch.
• Low/high salt: dose pool-grade salt to the AquaPure target or dilute for high salt; always re-test after a turnover before declaring done.
• Cold lockout: no action; production resumes when water exceeds the operating floor. Inform the owner it is seasonal.
• Scaled cell: soak per OEM (typically a dilute muriatic-acid solution) until fizzing stops, rinse, re-install; never scrape the plates.
• Wiring: clean and re-seat the cell connector, repair corroded pins, and confirm grounding.
• End-of-life cell: replace with the correct AquaPure cell for the model and pool size, set salinity to target, and recalibrate per the manual. Reset the cell-life or runtime counter if the power center tracks it, so future Service Cell warnings reflect the new cell.
• After any fix, raise the output percentage and confirm free chlorine is actually being produced over a turnover, not just that the alarm cleared. Re-test FC at the next visit to verify the generator is holding the pool, since a cleared LED with no chlorine production means the diagnosis was incomplete.

References

• Jandy, "AquaPure Electronic Salt Water Sanitization System Installation and Operation Manual" (Check System LEDs, cell cleaning, salt range, flow switch, and fault recovery).
• Jandy, "AquaPure Cell Replacement and Maintenance" service guidance (cell life, cleaning, and connector service).
• PHTA/APSP-11, "Standard for Water Quality in Public and Residential Pools and Spas" (chlorine and salinity parameters).
• NSF/ANSI 50, "Equipment and Chemicals for Swimming Pools, Spas, Hot Tubs, and Other Recreational Water Facilities" (chlorine generator equipment standards).