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Jacuzzi J325 Watchdog Error


desertcoast
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Hi - Frequent guest, first time asking for help. Thanks in advance and thanks for past help as a "browser"!

2006 Jacuzzi J325 owner here, bought from used spa dealer 3 years ago. Recent issue: working fine ( about 1 month past most recent water change) but came out to find the dreaded Watch Dog dashes error. 
Shut breaker off: upon power up, observed OH error code very briefly, temp was 102 (verified this, felt correct), red heater light comes on as though it's trying to get up to it's set temp of 104.
With panel off, I'm hearing what sounds like the circ pump trying to come on, but it never does. ( This circ pump has been a bit noisy over the past year so I've been suspecting it could fail soon).
If I leave it alone for several minutes, the watch dog dashes appear and the tub is locked.
Rinse repeat, same events but obviously the temp is starting to drop over the last 2 days of testing. Currently low 90's ( we're in Phx, high ambient temps).

So here's a detail: If I reboot as above and attempt to turn on the main pumps ( low and hi) they both work and the tub will operate with main pumps/ jets going for approx 5 min.....then watchdog kicks in and we start over.
All the while, that circ pump never seems to come on in any circumstance.
Steps:
Tested temp sensor ( replaced this 1 year ago) Good . Have a spare. It's good as well. Tested ohm reading based on a guide found here on this site.....both switches seemed correct for the temp at the time.
Tested Hi Limit switch ( ohm reading was about right for water temp at the time)
Flo Switch "looks" like it's working correctly but can't be certain. Replaced this 1 year ago.
Caps on control board "look" ok...not obviously bulging but I'm no expert. 
Fuse looks ok, but again...no expert here.
So I leave it to the pros.....am I suspecting the circ pump without due cause ( just because it's been noisy and seems to be struggling) or am I missing something else?


Thanks in advance!
 

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If the paddle in the flo switch is moving, than you have circulation which means the circ pump is running.   The motor itself could be turning on, but if the impeller isn't turning, it won't move water.  The jet pumps shouldn't activate the flo switch.

If the circ pump isn't running but the flo switch is somehow activated, the water in the heater will quickly heat up beyond 118 degrees and activate the hi-limit swich, which could lead to the watchdog error.  Watchdog error could also occur if either temp sensor or hi-limit sensor is bad. 

Dave

 

 

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Dave- Thanks for the reply. Your description helps me understand what I'm seeing. 

On closer observation: When I turn unit on, circ pump makes a series of intermittent groans and clicks, but never gets past that. I see short bursts of water running into the flow switch but nothing continuous. 

The flow switch paddle moves a little..fluttering but not actually making full sustained contact with the middle element ( meaning it's not really opening??  Pic attached)

Thanks again for the help!

Flow Switch.jpg

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In your photo, the flow switch is definitely open.  When it makes sustained contact with the middle element, it is closed.  When it's closed, it  tells the heater that it can turn on. 

For the flow switch to be installed properly,  the flow of water should push the paddle against the middle element.  There is an arrow molded into the plastic of the housing to show you the direction of the water flow.  If the paddle is almost touching but has a small flutter, the switch is probably working.  You can strip the wire and test for continuity with the tub turned on, it's only a 12VDC circuit and it's either on or off, no resistance is being measured so you can cut those wires and splice them without affecting the operation of the tub.  If you have continuity when the water's flowing, than the switch is operating properly.  Usually, you will get an FL1 error if the switch is bad;  watchdog means there's something going on that is hazardous to the bathers, like an overheat condition.

If you hear the pump and see the paddle moving erratically, it may be an obstruction in the line.  Often, that can be air, especially if you've drained the tub prior to the problem occurring.  Bleed the line by disconnecting it from the flow switch and letting some water flow out.  But once again, that should give you an FL1 error, not a watchdog error. 

Circ pumps are notorious for breakdown.  However, once again, a bad circ pump almost always gives an FL1 error, not a watchdog error.  The watchdog error usually means the hi limit sensor is tripping. 

I would un-mount the hi limit sensor from the heater and leave it just hanging outside the tub.  Then turn the tub on and see if the problem reoccurs.  Keep close watch on the heater to make sure it's not overheating, which can damage it.  You should be able to touch the metal of the heater when it's turned on.  If it's too hot to touch, the problem is not the hi limit sensor.  You were getting the watchdog because the heater is too hot.

If you get the watchdog error with the hi limit sensor unmounted, then you probably need a new hi limit sensor.  You can also grab the hi-limit sensor in your palm and see if it generates the watchdog error.  If it does, your hi-limit sensor is tripping at 98.6 which is too low.  Of course, if it doesn't trip the watchdog error, that doesn't prove it's good, it just proves it can tolerate 98.6 degrees.

One other problem I've seen is a heater relay on a circuit board goes bad and won't open.  In other words, it's always heating which will lead to overheat errors.  In those conditions, the water will get over 104 degrees, eventually tripping the hi-limit sensor somewhere around 118.  Hope that's not your problem, Jacuzzi circuit boards aren't cheap.

Dave

 

 

 

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Thanks..that gives me a few things to test. 

You wrote: 

Quote

You should be able to touch the metal of the heater when it's turned on.  If it's too hot to touch, the problem is not the hi limit sensor.  You were getting the watchdog because the heater is too hot.

Accidentally touched it once or twice during these tests and it was WAY too hot to touch...let out a pretty good YELP.

Thanks for the info. Will work through your tests and report back!

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I'm not sure my tests were telling of anything.

Spliced into the Flow Switch wire and upon power up, reading would eventually ramp up to 12v but would fluctuate wildly..often above 12v ( not sure how that's possible, maybe my meter is bad...) Circ pump never comes on; just a series of repeating 2 second "grunts" as though it's trying to come on. 

The tests are shorter now; watchdog error is usually kicking in within a minute...used to go longer than that. 

Metal heating element is scalding hot to the touch.

Tried freeing the hi-limit sensor. I had to abandon the test as I touched the flow switch and it was VERY hot to the touch and still didn't look like it was fully closed. Actually not even close with a half inch of space before making contact with the middle element. Fingers close to heater tube and it again felt scalding hot. Turned tub off.

Fairly confused at this point. I never hear the circ pump ever fully come on, but all the error codes and behavior don't cleanly point to any one particular problem.

Found a fairly inexpensive replacement pump ( same exact model) online so I may just swap that out anyway. It's been noisy for over a year and looks original.  Flow and Temp sensor are recently new so I may just begin replacing old parts until I solve this. Feeling like I'm chasing my tail now :)

 

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I guess I wasn't clear on the flow switch testing.  By putting your leads across the wires going to the flow switch, you are creating a path for the voltage to activate the heater circuit.  You need to cut the wire so you can check for continuity at the flo switch when water is still and when it's flowing.  IOW, you should have no continuity with the switch open and continuity with the switch closed.  (FYI, voltage between 12-15VDC is considered "normal."  That's what the transformer is supplying to the DC circuits.

But you actually said what the problem was.  The circ pump isn't coming on, the heater is overheating and the high limit sensor is tripping, giving you the watch dog error.  During normal heating, the heater will only go to 118 degrees, which is the maximum allowed temperature of the water.  You should be able to touch the heater with no problem at all.  In your case, however, there's no water moving through the heater so those few ounces in there are getting zapped with 15 AMPS at 240 volts and getting scalding hot, and tripping the hi limit sensor.

The real question is why is the heater coming on if there's no water moving to activate the flo switch.  If the flo switch is closed on power up, the spa will generate an FL2 error and stop.  If there's no flow of water, the switch isn't supposed to allow the heater to turn on, the circuit board is supposed to give you an FL1 error.

Next step - cut the flo switch wire.  The part that's connected to the switch you can ignore for now. 

First, power up the spa with the two leads separated.  You should get an FL1 error (some spas will give a FLO error).  If so, that's good.  With the power still on, twist the wires together.  The FL1 message should go away and the heater should turn on.  Since there's no water flo, it will overheat.  Power down the hot tub.  Your flo switch was most likely bad, because you have just performed the same action that a normally operating flo switch does and the spa reacted properly.

Now, twist together the two ends of the wire connected to the circuit board.  On power up, you should get an FL2 error.  If you do, and the heater doesn't turn on, your flo switch is bad. 

If the heater still turns on, you have a circuit board problem in addition to your circ pump problem.  Strange coincidence, but the circuit board isn't supposed to allow the heater to turn on if there's no flow.

Dave

 

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Really appreciate the help navigating this. This place is awesome! So I tried to follow all steps exactly; was a bit unclear on Test 3. If I did this last one incorrectly, I will re-do as needed.

Test 1. power up the spa with the two leads separated.  You should get an FLO error .  If so, that's good.  (YES FLO Error)
Test 2: With the power still on, twist the wires together. The FLO message should go away (YES)and the heater should turn on(YES).  Since there's no water flo, it will overheat(YES).  Power down the hot tub.  Your flo switch was most likely bad, because you have just performed the same action that a normally operating flo switch does and the spa reacted properly.


3. Now, twist together the two ends of the wire connected to the circuit board.  On power up, you should get an FLO error.  If you do, and the heater doesn't turn on, your flo switch is bad. If the heater still turns on, you have a circuit board problem in addition to your circ pump problem.  Strange coincidence, but the circuit board isn't supposed to allow the heater to turn on if there's no flow.
(unclear on wording here; taken literally it would appear to be the same as Test 2? )
Wondering if you meant I should re-connect the Flow Switch again in its normal state? If so test results:
Power Up>     Heater On-YES>     FLO Error> YES after approx 20 seconds, not immediately> watchdog shutoff.
So does this suggest:
Bad Circ Pump, possibly bad Flo Switch and circuit board? That would really be an unfortunate series of events :)
 

Thanks again for the walk through. You're being very generous with your time..it's much appreciated!

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The whole point of this was to see if the problem was with the flo switch or the circuit board.

Step 1 tested that the circuit board was able to recognize the flo switch open.  It did.

Step 2 tested that the circuit board was able to recognize the flo switch closed.  It did.

Step 3 tests the circuit board.  If the circuit board sees the flo switch activated BEFORE the circ pump turns on, it thinks the flo switch is bad and should shut down and give you a FL2 error.  By twisting the red and black leads together on the circuit board side of the flo switch wire, you are faking the flo switch being closed with no circ pump action, generating the FL2.

If the spa starts up with the flo switch closed (which we faked by wires twisted together) it indicates that the circuit board isn't interpreting the signal from the flo switch properly.

Summing up, your circuit board can read the flo switch being open and closed (steps 1 and 2).  But it isn't reacting properly to the hot tub starting up with the flo switch being closed which indicates a problem in the circuit board.

Here's a video about flo switches that might help if I'm not explaining it well: 

 

Dave

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Ah, that makes perfect sense ( and you're explaining it brilliantly..thank you)

I did that test as well:

3. Now, twist together the two ends of the wire connected to the circuit board.  On power up, you should get an FLO error (YES)  If you do, and the heater doesn't turn on, your flo switch is bad. If the heater still turns on (Yes it does), you have a circuit board problem in addition to your circ pump problem.  Strange coincidence, but the circuit board isn't supposed to allow the heater to turn on if there's no flow.

So...

When the circuit board thinks the Flow Switch is closed by twisting leads together:  Startup>FLO Error>Heater ON> OH Error>Watchdog (Circ Pump making no sound)

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I've never seen a circuit board and circ pump die simultaneously.  My recommendation would be to replace the circ pump.  Even though the circuit board isn't reacting properly, let's see how it acts when the circ pump is replaced.  Before replacing the circ pump:

1) Check all the wiring to the circ pump to insure there are no broken or burnt wires.

2) Disconnect the circ pump from the circuit board, then plug it into a standard wall outlet.  Obviously, be careful.  Let's see if that gets the circ pump working.  If not, replace the circ pump.

With the new circ pump, I'm assuming your hot tub will start up normally and begin to heat.  When it reaches 104 degrees (or whatever you have it set for) the heater should turn off, even though the circ pump stays on. If it continues to heat beyond your set temperature,  it's probably time for a new circuit board.  Once it hits 118 degrees, you will get the watchdog error. 

If the hot tub stops heating at the set temperature, the problem is probably in the circuit board logic, it just isn't reading the flow switch.  If it continues heating, the problem is probably in the heater relay; it won't open up.

Either way, you 'll need to repair or replace the circuit board.

Dave

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Dave- Thanks again for the walk-through. I did a fair amount of research on watchdog errors and it did seem like my situation didn't match up exactly with others I read about. Maybe the possibility of multiple components being in play would explain that.

Either way, yes I ordered the circ pump and should have it in a few days. BTW, yes I will heed all safety warnings here and would caution others reading this in the future to do same. I work in audio and do a fair amount of wiring and troubleshooting in my wheelhouse but I usually default back to being pretty cautious when I'm out of my field. At any point I ever feel I'm in too deep I'm never opposed to calling the expert to finish the job ( someone like you, but in Phx AZ  : )    )

Will update when circ pump arrives so others who happen upon this thread will have closure :)

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Quick follow up on this:

New Circ pump installed, in general all things back to normal. Watchdog error gone. One caveat:

I do still get an occasional FL2 error but it's in a very specific situation and I believe it may be intended.

My FL2 error only occurs when the circ pump ( or circ pump/heater combination) turns off. My understanding is that the circ pump would only turn off when the unit goes into "Summer Logic" mode ( where ambient temp is such that no additional heating is needed).

I live in Phx, and many months of the year it's warm enough that Summer Logic mode might be triggered. Nothing on the display says this explicitly...but I'm guessing this is what accounts for the occasional observation that the circ pump has shut down. It's definitely the exception; most of the time when I check on it, it is running. FL2 only shows when it is not running...and in fact the flow switch is indeed open ( hence the notification).

So unless I'm reading that situation incorrectly, I believe everything is working as it should.

New pump is much quieter, barely know it's on. All in all, quite happy having my spa back.

Dave, much appreciated all the help with this. I promise to pay if forward with some other lost soul in my chosen field...I'll help someone out through their crisis as you did here. This place is awesome!!

 

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