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Billy, Technician
Category: Pool and Spa
Satisfied Customers: 22422
Experience:  Licensed in Hydronics and Boilers
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First time trying this: I have a Jacuzzi Z145 (1999

Customer Question

First time trying this: I have a Jacuzzi Z145 (1999 vintage), w temp control knob and one push button. Tub will overheat and then shut down, with the status/heat LED blinking. Looking for tips to t/s either the thermostat, high limit switch or control panel? Paul here
Submitted: 1 year ago.
Category: Pool and Spa
Expert:  Billy replied 1 year ago.


to over heat means :

slow pump, bad sensor, bad thermostat control.

How fast does it overheat?

Customer: replied 1 year ago.
If I fill the tub, and restart the spa, and have the rheostat on the control panel set to the same spot I always use, the tub will heat up at the normal rate, but will not stop. It appears that the overheat sensor is shutting down the unit when the overheat temp is reached. The pump circulation appears totally normal, the flow sensor appears to be working (if the filter is clogged, for example, the unit will turn off the heater appropriately). My question specifically is I measured the resistance of the tub temperature sensor (located near the filter). It measured roughly 33KOhm at ambient temp (hot tub not on). I then heated this sensor (guess it is a thermistor type?) to see if the resistance changed. As it warmed up, the resistance decreased. I am suspecting the rheostat on the control panel. I have removed the cover to the spa controller box and can unplug the cable to the control panel. Would you know what leads on the plug (looks like an ethernet plug) would be the rheostat? And how to determine if this is the defective component? Also does the resistance measurement on the hot tub sensor seem OK and indicate that the sensor is working properly? Note that I have an analog control, with a simple dial temperature setting, and a single push button and one led status lite. THanks.