Pump didn't come on - AQL-P-4 controller

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Scout101

Scout101

Well-known member
Aug 18, 2015
263
North Kingstown, RI
Hi, hoping for a little group knowledge. My pool pump didn't come on this morning with the timer (shut off last night as usual as far as I can tell). AQL-P-4 control system, salt cell, that's about it. Controller SAYS it's turning the pump on and off, but nothing actually happens. When i opened things up, appears that the K1 relay is a bit scorched in the back. I THOUGHT that was for the salt cell (common problem with no cell power, but cell was working fine yesterday), but does that K1 relay have any control of whether the pump gets activated (opening the high voltage relay below it)?

Anyone know where to find a schematic for this board?

If the relay itself is dead, what do the K2 and K3 relays control? Aside from pump, SWG, and lights, there's not much else in my system (technically a heater but it is disabled). Wondering if I can steal one of those relays as a substitute?

I'm scheduled to be on vacation for a week starting this evening, so while better than happening tomorrow, it's pretty poor timing for trying to get the pool working so it's not green when I return. Appreciate any help!
 
quick looking through the internet seems to imply K1 powers the SWG, and K2/K3 are involved in switching polarity so would be bad candidates for swapping. Does that sound right? What else would result in pool pump not kicking on when the controller signals it?
 
The filter pump relay is indicated on the bar.

Red dots are line in and blue are load out.

Red should always have 240 volts and blue should have 240 volts only when the relay is on.

Do you get 240 on line in and load out?

The top 2 terminals should have 24 volts dc only when the relay is on.

Do you have an unused relay?

You can swap in an unused relay or get a new relay.

You can move the pump line wires from the load out terminals to the line terminals to control the pump from the breaker.

Do you know how to work on things like this safely?

1721398656638.png

Prologic.jpeg

Prologic relay.jpeg
 
Measuring from red to black top terminals, you should get 24 volts DC when the relay is on.

That is the coil voltage from the board to close the relay.


1721399419265.png

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i see 240 on the OUT pair, not on the IN pair. will go check 24V side. Turning on via controller didn't change the other 240v reading. If you think that's where the failure is, definitely think I've got unused ones there but will check.

Is it possible that the installer wired the In/Out backwards? That's what kinda matches what I see (with OUT always on, IN not moving from zero).

I've got 2 unused relays from what I can see (Aux1 and Aux2 only have the top 24V wired, there's nothing on the bottom of those relays.
 
Swapped relay, still not getting any output power and not seeing 24v. Board seems to have good input power, but not getting the power out to kick the relays. Also seeing cell power error for the SWG now, even after resoldering the relay. Wondering if it blew out, or there’s damage to the back of the board causing things now…
 

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JamesW said:
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Thanks, that's helpful. Looking like I've got good power to the board, good power coming out of the rectifiers, questionable action around the K1 relay, and then not seeing 24V at the low side of either the pump or light relays. POSSIBLE that both of those relays (somewhere in the K4-K8 range) are bad, but suspect I'm going to start chasing my tail. Would K1 being blown out cause any other downstream problems, or is that isolated to SWG operations only? In addition to either failure or a hotspot that flaired up there, it looks like there may have been damage to the board itself behind it. Almost a little delamination of the board there, so concerned that it's pooched. Could try swapping the relay itself, but don't think (may be wrong) that one is connected to my other issues...

Certainly open to any other cheap/easy fixes to try, but given the age of the board (2006-2008 era), it may be time to consider an upgrade. Multiple spots on that flowchart led to "replace main board" when I followed my symptoms...

If this one is not salvagable, are there recommendations for what a good/reasonable replacement system would be? I've got the pump, one set of 2 lights (which don't work currently but that's a problem with the lights themselves), the SWG, and currently have an old dead NG heater that I plan to replace with a newer NG heater next season. Don't anticipate adding any other features, so don't need a super complicated system, but would love at least an app or other functional method of controlling the pool without going out to push the button. App would be idea so I can check pool status when away instead of looking at a camera.

Thanks for all your help, this site is the best!
 
You can move the pump wires to the Relay Line Terminals with the Power Wires so that you can turn the pump on and off with the breaker for now until you can get the system working again.
 
Yes, no 24v DC at the relay coil that i can see (referring to the top two points on the large pump relay, yes?). Purple 3A fuse shows good continuity, so doesn't appear to be blown, I was hoping that may be a cheap/easy fix. No change in voltages when engaging/disengaging pump via the controller. Nice burning smell the first time i opened the enclosure, though, and one of the 4 standoffs for the control screen got a bit scorched too, so it definitely had a failure or hotspot happen there.

In addition to the pump not seeing voltage, I'm not getting voltage to activate the light relay either (next big power relay next to it). I've got a damaged light, so normally it blows the breaker every time I activate the lights via the controller button, but it doesn't do anything now. All pointing to the power source upstream activating these relays. I swapped a relay with unused Aux2, but no difference.

Since the Salt Cell is reporting no power (and also not reading any salt, which is not correct), pretty sure that K1 relay itself is damaged if not the board itself underneath it as well. Given that the SWG doesn't work and the pump isn't controllable, I wire-nutted the Pump's in and out wires together so that it's permanently on when the breaker is engaged. That should at least get me through my week away until I can come home and make more permanent fixes. I'll eat the electric bill, was already running 10 hrs a day so is what it is. without the controller doing anything, left that breaker off entirely just to eliminate any power/fire issues if things go badly while I'm gone. Bought a floater and some pucks, should tide me over for the week...

With how much chlorine pucks are, definitely glad I (usually) have a SWG. No brainer at these costs, and bought it a couple years ago when it was even cheaper...
 
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Scout101 said:
Would you recommend even bothering with a 1-1 replacement of that entire board if I can't narrow down the failure or it's irreparable, or should I be looking at something made in the last decade or so and upgrade?
Click to expand...
Either way is fine and it depends on what works best for you.

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@JamesW has you all squared away. If all the power is good and the relays aren't getting 24 vdc to actuate them, the fault can only be on the board. The photos show rust and corrosion consistent with condensation or water intrusion over the years. It's fairly likely the high current SWG part of the controls finally arced, and that fried all the relay drivers on the controller IC. Almost certainly not economical to repair even if you're skilled in that direction.

Regardless of how you repair, do check for water ingress. Would be a shame to have a new board go the same route. Cheers!
 
Definitely appreciate the support, sounds like we're on the same page and your thoughts on why are pretty likely. Bought the OmniPL upgrade kit and will hopefully install soon. Pool survived the week vacation with the pump hardwired and pucks in a floater, so hopefully will be a relatively straightforward upgrade and i'll be back in business (now with WiFi/app capability!). Will check for water intrusion, but nothing was immediately apparent. Last board was circa 2008, so suspect time/age just eventually got the better of it.
 

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