This newly designed high limit thermistor replaces the original black plastic-tipped version. It is a safety device that will shut down power to the spa if the water temperature exiting the heater is too hot. This would indicate a “low water flow” condition. Secondly, if this sensor is faulty then the spa can shut down requiring you to shut off power to the spa, then re-establish power in order to reset the unit. This thermistor is for Hot Spot spa models beginning in 2006, (except Sprint & Dash) and all Solana spa models beginning in 2006.
1. Set the meter to 20K on the OHM scale.
2. Record the temperature of the spa water.
3. Unplug the thermistor from the control box.
4. Meter across the two Thermistor leads.
5. Refer to the Temperature versus Resistance chart below to find the correct resistance value for the temperature measured. If the temperature and resistance does not match that of the chart, this test has failed and the thermistor must be replaced. Remember if the spa has been inactive, the spa water temperature may be different than the water temperature in the heater housing.