Display shows COOL, and the water temperature is significantly below the setpoint; the heater may be limited.

Possible Causes

Recent refill with cold water, economy or sleep mode active, undersized power supply (120V mode), heater not energizing continuously

Safety first: Ensure proper electrical configuration before changing modes.

Verify mode: Set the spa to Standard mode so it can heat continuously.
Check power configuration: If running on 120V, heat-up will be slow. Consider wiring to 240V per Master Spas specifications for faster heating.
Keep cover closed: Close and latch the cover to minimize heat loss.
Monitor heater indicator: Confirm the heater icon or indicator is on when the spa is calling for heat. If not, troubleshoot the heater and control pack.

Easy 2/5