F3
MSPA
Heater Relay or Triac Fault
Display shows F3; spa may shut down or lock out heating.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Stuck heater relay on MSPA control PCB, Shorted triac driving heater, Burnt relay contacts, PCB trace damage in heater circuit
How to Fix / Troubleshooting
Safety first: This fault involves mains voltage. If you are not experienced with electronics, contact a professional.
- Observe heater behavior: If the heater stays on even when the set temperature is reached or when the spa is off, the relay is likely stuck closed.
- Inspect PCB: With power disconnected, open the control box and visually inspect the heater relay area. Look for burn marks, melted plastic, or cracked solder joints.
- Check for shorts: Use a multimeter to check continuity across the heater relay contacts with the spa unplugged. If continuity is present when the relay should be open, the relay is stuck.
- Replace control PCB or relay: On most MSPA units, the relay is soldered to the PCB and the entire MSPA main control PCB is replaced as a unit. If you have soldering skills and parts, you may replace the relay with an identical rated component.
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Repair Difficulty
Professional Required
5/5
Required Part
MSPA Main Control PCB
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