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Thermistor, High-Limit, Hot Spring, Tiger River, Limelight, 2002.5-current

Item #: 79005

Thermistor, High-Limit, Hot Spring, Tiger River, Limelight, 2002.5-current


Replaces the obsolete 39525 and obsolete 39204

Newly designed and includes o-ring. This high-limit thermistor sensor is a safety device designed to communicate with the system to shut down the heater if the water temperature exiting your heater exceeds 118 degrees F. It simply screws into the No Fault Heater Housing (hand tight only) and then plugs directly onto the motherboard inside the IQ 2020 control box. (If your existing thermistor plugs into the side of the spa's control box see item 38416). Always replace thermistors in pairs (ie; 39204 & 79006 ). Please use the "Check Serial Number Compatibility" widget below to confirm that this part is compatible with your spa.

Note: ALWAYS REPLACE THE THERMISTORS IN PAIRS. If a new thermistor differs in temperature sensing more than five degrees from the old thermistor, the system will go into a "fault mode" and prevent the heater, jet pump(s) and light from operating. So again, when replacing a control thermostat thermistor always replace the high limit thermistor as well and vice versa.

Test Procedure
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.

This chart shows the OHM range of the thermistor
Click to enlarge
Printable PDF

Check Serial Number Compatibility