Spa will not heat; water stays cold even though pumps run and set temperature is higher than actual.

Safety: Turn off power at the GFCI breaker before opening the equipment bay or touching electrical parts.

• Step 1 – Verify settings: Confirm the spa is in Standard mode (not Economy/Sleep) and that the set temperature is above the current water temperature.
• Step 2 – Check for heat indicator: On many AquaRest topside panels, a heat icon or indicator light shows when the heater is commanded on. If this never appears, suspect sensors, flow switch, or control logic.
• Step 3 – Confirm water flow: Ensure strong flow from heater return jets with the pump running. Clean or remove the filter and open all slice valves.
• Step 4 – Inspect heater and wiring: With power off, open the control pack and check heater terminals and wiring for burns or loose connections.
• Step 5 – Test heater element: If qualified, measure resistance across the heater terminals. A very high or infinite reading indicates a failed element that must be replaced.

If the heater tests good but still does not energize when the heat icon is on, the control board or heater relay likely needs professional service.