Display shows Prr or PR and spa may not heat or may shut down

Safety first: Turn off power at the breaker before touching any electrical components.

• Locate pressure switch: On some Master Spas models, a pressure switch is threaded into the heater manifold with two small wires going to the control pack.
• Check flow first: Ensure filters are clean, water level is correct, and pumps are primed. Low flow can cause pressure switch errors.
• Inspect wiring: Verify the pressure switch wires are firmly connected and not corroded or damaged.
• Adjustment (if adjustable type): Some switches have an adjustment screw. Only make small 1/8-turn adjustments and test. Do not over-adjust to defeat safety.
• Replace switch: If the switch does not open/close reliably with pump operation, replace it with a compatible Master Spas pressure switch.
• Control pack issue: If a new switch and good flow still produce Prr, the control board may be faulty and should be evaluated by a spa technician.