Cyclejim13 Posted November 8, 2021 Report Share Posted November 8, 2021 My Jacuzzi J315 (120v) has started going into Watchdog mode within about an hour of startup. I changed water about a month ago and it was working fine. I was in it for an extended period of time and noticed the water seemed to be a little cool, checked the temp and saw the (---) watchdog mode. I cycled the power and it came back on and showed 95 degrees. I let it heat for a while and it was up to 98 then the next check it was back to (---). Power cycled again and found it was going back to watchdog in about an hour or so. Next I pulled the filters to see if that would help. It did. It heated up to 102 where it was set and stayed there for 2 days. I concluded the filters needed changing (at least 3 years old from when I bought the house with tub) and got new ones. Put the new filters in and it seemed to be working as expected - heating up normally. Then I checked one time and saw the displaying alternating between "oH" and "116" then it went into watchdog mode and the cycle started again: watchdog, power cycle good for an hour or so then watchdog again. Pulled the filters and it works fine. With the filters out everything seems to work fine, the temperature stays where it's set, the water seems to be recirculating and I see bubbles coming up from the return. I should note that the recirculation pump was replaced less than a year ago and seems to work fine. This seems like some sort of sensor issue to me as nothing really seems to not work, except for the watchdog mode coming on. The fact that it works with filters out but the watchdog comes back with filters in makes me wonder if there is some sort of flow problem and the filters add just enough resistance to push it over the edge and cause the watchdog error. Anyone seen this kind of behavior or can suggest how to definitively determine the cause and fix it? Quote Link to comment Share on other sites More sharing options...
ciderjack Posted November 8, 2021 Report Share Posted November 8, 2021 3 hours ago, Cyclejim13 said: My Jacuzzi J315 (120v) has started going into Watchdog mode within about an hour of startup. I changed water about a month ago and it was working fine. I was in it for an extended period of time and noticed the water seemed to be a little cool, checked the temp and saw the (---) watchdog mode. I cycled the power and it came back on and showed 95 degrees. I let it heat for a while and it was up to 98 then the next check it was back to (---). Power cycled again and found it was going back to watchdog in about an hour or so. Next I pulled the filters to see if that would help. It did. It heated up to 102 where it was set and stayed there for 2 days. I concluded the filters needed changing (at least 3 years old from when I bought the house with tub) and got new ones. Put the new filters in and it seemed to be working as expected - heating up normally. Then I checked one time and saw the displaying alternating between "oH" and "116" then it went into watchdog mode and the cycle started again: watchdog, power cycle good for an hour or so then watchdog again. Pulled the filters and it works fine. With the filters out everything seems to work fine, the temperature stays where it's set, the water seems to be recirculating and I see bubbles coming up from the return. I should note that the recirculation pump was replaced less than a year ago and seems to work fine. This seems like some sort of sensor issue to me as nothing really seems to not work, except for the watchdog mode coming on. The fact that it works with filters out but the watchdog comes back with filters in makes me wonder if there is some sort of flow problem and the filters add just enough resistance to push it over the edge and cause the watchdog error. Anyone seen this kind of behavior or can suggest how to definitively determine the cause and fix it? Was the water actually 116? Quote Link to comment Share on other sites More sharing options...
Cyclejim13 Posted November 8, 2021 Author Report Share Posted November 8, 2021 The water was not 116. I didn't drop a thermometer in it at the time but it felt normal. I just checked it now and it is within 1 degree of the setting (103). The regular cycle of circulation pump is running at the moment with the filters removed. It seems normal with the filters out. Quote Link to comment Share on other sites More sharing options...
CanadianSpaTech Posted November 8, 2021 Report Share Posted November 8, 2021 Some odd behavior but I'm going to guess temp sensor going south. Is it located in the filter housing on the side wall? 1 Quote Link to comment Share on other sites More sharing options...
Cyclejim13 Posted November 9, 2021 Author Report Share Posted November 9, 2021 Thanks CanadianSpaTech, that's where I was leaning as well, based on what I have read. It doesn't seem to fully explain it but the part is relatively inexpensive so I think I'll try replacing the temperature sensor and see what happens. Quote Link to comment Share on other sites More sharing options...
CanadianSpaTech Posted November 9, 2021 Report Share Posted November 9, 2021 Post results please Quote Link to comment Share on other sites More sharing options...
Cyclejim13 Posted November 21, 2021 Author Report Share Posted November 21, 2021 A new temperature sensor seems to have fixed this. It turns out getting normal behavior with the filters out was short-lived. It continued to go into watchdog mode regularly with time between failures decreasing. Replaced the temperature sensor and no problems for about a day now. I expect that will continue. 1 Quote Link to comment Share on other sites More sharing options...
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