Pentair Probe Thermistor, Defrost Sensor | ThermalFlo HP Titanium & UltraTemp Heat Pumps | 473665Z

The Pentair Probe Thermistor Defrost Sensor (473665Z) is the OEM replacement defrost sensor for the Pentair ThermalFlo HP Titanium and UltraTemp heat pump series.

⚠️ IMPORTANT: LICENSED PROFESSIONAL INSTALLATION REQUIRED
Heat pump components must be serviced by a licensed pool professional or qualified HVAC technician. Do not attempt to service high-voltage or refrigeration-circuit components without proper certification.

This thermistor probe monitors refrigerant or coil temperature during the defrost cycle, signaling the heat pump's control board to initiate or terminate defrost operation as needed. A failed or out-of-tolerance defrost sensor can cause the unit to run continuous defrost cycles, fail to defrost at all, or display a fault code — resulting in reduced heating efficiency or a unit lockout. Replacing this sensor with the correct OEM part restores accurate temperature sensing and normal defrost cycle behavior.

Specifications

Fits Into

Compatibility is based on Pentair parts documentation and available OEM records. This is not an exhaustive list. For certainty, verify the part number in your equipment's manual or on the original part itself before ordering.

Pro Tip

Before ordering, locate the part number on your existing sensor — it is typically printed or molded on the probe body or connector housing. Confirm it matches 473665Z. When replacing the defrost sensor, have your technician inspect the sensor wiring harness and connector for corrosion or heat damage at the same time; a compromised connector can cause the same fault symptoms as a failed sensor and is inexpensive to address during the same service call.