Spa will not heat; water stays cold even though pumps run and no error code is displayed.

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

• Step 1 – Check settings: Verify the set temperature on the Nordic topside panel is higher than current water temperature. Ensure the spa is not in economy or sleep mode, which limits heating.
• Step 2 – Observe heater indicator: When the spa calls for heat, look for a heater icon or indicator light on the topside. If it never appears, the control may not be calling for heat.
• Step 3 – Feel heater tube: After 15–20 minutes of supposed heating, carefully feel the metal heater tube in the equipment bay (do not touch bare terminals). It should be warm if heating.
• Step 4 – Test heater element: With power off and heater wires removed, measure resistance across the heater terminals. An open circuit indicates a failed heater.
• Step 5 – Check sensors: If the control thinks the water is already hot, it will not energize the heater. Compare displayed temperature to an external thermometer; if the display is much higher, replace the temperature sensor.
• Step 6 – Inspect control board: If the heater and sensors test good but the heater never receives power, the heater relay or control board may be defective and require replacement.