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Older Spa Crest tub. No heat. No heat indicator light.


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I have an old Spa Crest spa with a Spa Builders AP1 control and heating unit.  Everything works except the heat.  The heating element tests good with the multimeter.  I am not getting any current to the lugs on the element, however.  The air switch also tests good with the meter.  Both contactors inside the control unit are new.  The reset switch for overheating tests good.  Not sure what to test next.  This is a mid nineties tub in otherwise good condition.  Any help is greatly appreciated!

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Sounds to me like the control board is not calling for heat, thus the lack of heater light nor power to the lugs.

My guess (and it's just a wild one at this point), is the temperature sensors.  They could have failed or failing, so the tub "thinks" everything is fine and the water is at-temp when it's really not.  Temp sensor failures are common and easy to test/replace as needed from what I understand although I really don't know much about older tubs but I'd imagine they'd use similar sensors.

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I will get photos as soon as the weather allows.  

As for the contactors...  Before the tub stopped heating, the contactors started clacking non stop.  So in hopes to prevent further damage I cut the breaker to the tub and shut it off.  This unit has two contactors.  One is a pole and a half.  The other is a two pole.  When I began troubleshooting, I determined the two pole wasn't making connection on one side.  When I removed it, I took the cover off and the contactor fell apart.  One side was completely broken and in pieces.  I thought I had discovered the problem.  However, upon replacing the contactor I still have no heat or light.  Note:  the control panel on this unit has a "ready" and "heat" light, both of which are dark at all times.  The "jet" and "blower" lights both are still on and both those features function correctly.  

I do not see a flow switch like the one in the photo above anywhere on the unit.  

I do have a multimeter.  

Thank you all for the comments and feedback!

 

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That flow switch is rare, and you likely have a pressure switch attached to your heater. You'll need to get in there with a voltmeter and figure out where the power dies. This means working on it with the power on. If you are not comfortable with that, hire someone who is. These old school packs are dangerous, especially if not on a gfci breaker, which was not required back in the day.

Typically these packs have a thermostat relay, that turns on low speed pump if the thermostat closes. Then the pressure switch and sometimes high-limit switch control one contactor and the thermostat controls the other, but these are independant components and can be wired in a number of ways. 

Contactor chattering is often a faulty thermostat or maybe pressure switch or coil resistor. Post those pics and I can walk you through testing.

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Update:

Upon further inspection, I discovered the pressure switch is stuck open.  The plunger which is activated by the water pressure is stuck at the bottom and doesn't come up.  But even when I manipulate the switch manually I don't show connection on the meter.  So a replacement switch is ordered and hopefully on the way.  

We'll see if this solves the problem.  I have a feeling there could be more issues.  

I'll update as soon as I get it installed.  

Thank you all for the help!

 

 

 

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Found the problem, but don't know the cause of it yet.  In the photo you can see both the two pole contactor and the pole and a half contactor.  Both are new.  The red wire connected to the top of the two pole is not getting any power.  I took the cover off the contactor, pushed it in manually, and I get heat and the light.  Checked with the meter at the actual heater and full voltage is there.  The contactor on the right is working and the yellow wire is hot.  I put the yellow wire  on the two pole contactor to test it and the contacts pulled in like they are supposed to.  So I know the contactor is good.  The culprit is the red wire with no power.  I've traced it back as far as I can through the pressure switch all the way to the cover panel with the timer and I have continuity throughout.  This is as far as I got.  I can't determine where the power loss to the red wire is.  Any ideas?  Thanks again!

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You need to find where you are losing power and why. 

It's hard to track wires by phone, but those systems usually have a wiring diagram somewhere, usually on the cover or in a small bag attached to the side or back of the box. If you can find that it would help.

Those systems usually have a relay or switch that turns off power to the pressure switch/ thermostat and timer, and hence the low speed pump and heater, when the high speed pump is on. They can also be wired to allow the heater to run, but still have to shut off low to run high. I'd guess the bottom right 2-pole switch just above the pressure switch is the one, but I'm not sure without a diagram or being there myself.

They can have a switch to bypass the timer and let it heat whenever it needs to, or turn the heater off entirely. This can be in the face of the timer or the pack cover. Check for that.

 

 

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  • 2 weeks later...

It has a rocker switch on the outside of the panel.  I can switch it to all three positions and still don't get any power.  I tested the switch and it checks good.  So it appears the problem is elsewhere.  Could it be the temp probe?  I don't even know where it is at this point.  But hopefully it isn't impossible to reach.  Thanks!

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