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kevdev

Jet Pump Short Cycles

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kevdev    0

Sundance Capri, 1999, single jet pump.  The pump comes on for 1 second (louder than normal) then shuts off.  About 5 seconds later it tries again and shuts off after a second.  During that short time that it us running water is seen coming out of the jets so I believe the pump is pumping.  I disconnected the motor wiring and can hear the control board relays working properly (the relays are not short cycling, they come on and stay on). 

Any ideas or suggestions?

 

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Based on the age of the spa, I'm assuming you're talking about electro-mechanical relays, is that correct?

How do you know the relay's come on and stay on?  You hear them click, but do you know they are passing power?  I would put my voltmeter on the pump connection in the control box, press the button, and see if the relay remains closed.  If it closes and then immediately opens, the problem may be in the relay, not the pump.  Or in the circuit providing the cycling voltage to the pump relay.

If the relays are correctly sending power to the pump, the pump motor probably has a thermal overload switch.  The switch may be bad, or the motor may be bad and triggering the switch.  The pump shuts down, waits a minute and tries to turn on again.  The fact that you said "louder than normal" sounds like the pump is struggling to turn, which would be a symptom of a bad thermal overload.  Would you say it's the sound of the motor rotating, or is more like a loud "hummmm"

 

 

 

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kevdev    0

Thanks for the response Dave.  When the motor does come on, it and the impeller are indeed rotating because I see water rushing from the jets for the short amount of time that the motor runs.  There are two relays involved one for slow and one for high speed and the motor short cycles on both speeds.  Still I will check the relays as you suggest (would hate to spend $400 for a pump without being absolutely sure :).    

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kevdev    0

I tested the relays as you recommended.  They behave properly (they stay on when energized).  I did not test them with the pump connected as I don't want it cycling on/off.  There are two relays and they both behave the same.  

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If you press the JETS button, the relay's activate, the pumps run then stop, and you are still getting voltage coming out of the relay's, then something in the pump must be causing it to turn off.

Is this a 115VAC or 220VAC pump?

You could try connecting the pump directly to an outlet outside the hot tub.  About half the times I do that, a 230VAC pump will run from a 115VAC outlet.  I wouldn't do it for more than a few seconds, but it would be a way to test the motor outside of the spa electronics to verify it's a problem before buying a new pump.  Of course, if it's a 115VAC pump, you'll know for sure.

 

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kevdev    0

I tested the relays with the pump connected and they did stay energized and supplied power to the pump when the motor stopped.  So I'm confident it's the pump motor.  It would be nice if it was something as simple as the starting capacitor or a faulty thermal switch.

The spa is keeping itself clean with just the recirculating pump so I'll wait until after winter to drain it and pull the big pump to see if I can see what's going on.

I'll update the forum when I do that. 

Thanks for your help ScubaDave!

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