Raypak pool heat pump or pump/heat combo displays LP and will not heat; unit may attempt to start and then shut down.

Safety first: Turn off power at the breaker before removing any access panels. Do not attempt to connect gauges or add refrigerant unless you are licensed.

• Check ambient conditions: Verify outdoor temperature is within the Raypak heat pump's operating range (typically above ~45°F/7°C). In very cold weather, LP can be normal; wait for warmer conditions.
• Inspect airflow: Ensure the fan is running freely, the top grill is clear, and there is no obstruction around the unit. Poor airflow can cause abnormal pressures.
• Power cycle: Turn the unit off at the breaker for 5 minutes, then restore power and attempt to restart. Watch for LP reappearing immediately.
• Check water flow: Confirm the circulation pump is running and that the Raypak unit is getting adequate water flow (clean filter, open valves). Some models will trip LP if water flow is extremely low and evaporator temperature drops.
• When to call a pro: Persistent LP usually indicates low refrigerant or a faulty low‑pressure switch. Contact a Raypak‑authorized HVAC/pool technician to leak‑check, repair, and recharge the system.