Sundance Spas Circuit Board Troublshooting Problems, Symptoms, Causes & Fixes

Click a question below to jump to the answer:

• Why won’t my Sundance spa heat?
• What do Sundance error codes mean?
• Why does my GFCI trip?
• Why does my pump run on its own?
• Why is my display acting strangely?
• Why don’t the spa buttons respond?
• Why are power connections burned or melted?
• Helpful tips most Sundance owners aren’t told

Why won’t my Sundance spa heat?

Symptoms: Heat light on/off, no water heating, error codes like FLO or FL.

Causes & Sundance Fixes:

• Pressure switch open: Test the pressure switch. Replace if defective.
• Low water flow: Clean filters, open jets, remove debris from pump.
• Faulty heater: Test voltage at heater terminals. Replace heating element if 220V is present but no heat.
• Defective Sundance circuit board: If heat light stays off and pressure switch works, replace the circuit board.

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What do Sundance error codes mean?

Symptoms: Error codes like FLO, FL, HF, 3 blinking dots, or temperature faults.

Causes & Fixes:

• FLO / FL – Insufficient water flow: Clean filters, open jets, remove pump debris.
• HF – High-limit tripped: Check heater and sensors for proper function.
• 3 blinking dots – Flow sensor or pressure switch issue: Test sensor or switch and replace if defective.

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Why does my GFCI trip?

Symptoms: Spa loses power, GFCI breaker trips repeatedly.

Causes & Fixes:

• Shorted heater: Disconnect heater wires and test. Replace if GFCI stops tripping.
• Faulty topside control or spa components: Unplug components one at a time to identify the faulty part.
• Defective circuit board: If GFCI still trips after all components are unplugged, replace the circuit board.

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Why does my Sundance spa pump run on its own?

Symptoms: Pump starts randomly without buttons pressed.

Causes & Fixes:

• Faulty topside control: Unplug and test. Replace if problem stops.
• Moisture in topside control: Dry or replace the topside control.
• Defective circuit board: If topside control is fine, test board and replace if needed.

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Why is my Sundance spa display acting strangely?

Symptoms: Flickering, unresponsive buttons, random error codes.

Causes & Fixes:

• Topside control failure: Replace topside control if display behaves erratically.
• Circuit board issues: Test and replace the board if topside control is fine.

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Why don’t the spa buttons respond?

Symptoms: No response from spa-side buttons, circulation pump doesn’t start.

Causes & Fixes:

• Check topside control cables for damage or rodent chewing.
• Unplug topside control. If circulation pump starts within 1 min, replace topside control if defective.
• Check voltage and fuses with a multimeter.

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Why are power connections burned or melted?

Symptoms: Burned terminals, melted wiring, or relay damage.

Causes & Fixes:

• Loose main power or heater connections → tighten to 30–35 inch-pounds.
• Check relays and termination wiring; replace defective components.

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Helpful tips most Sundance owners aren’t told

• Always check for loose connections before replacing boards.
• Moisture in topside controls is a common cause of strange behavior.
• Regular filter and jet maintenance prevents error codes and heater issues.