"AO" Error on Hayward H400IDL2 Heater

Jump to latest Follow Reply
J

jleonard711

Member
May 3, 2015
17
AZ
I have a 12 year old Hayward H400IDL2 heater which I practically entirely rebuilt last year - new blower, control board, vacuum/pressure switches, and exchanger. I only needed to replace the blower (it had started rusting out), but I got a crazy deal on those other parts so I figured I might as well swap them out as well as long as I'm taking it apart. The heater worked perfectly after installing all the parts with no issues, and the last time it was used is about 6 months ago.

This past weekend I fired it up for the first time this winter (I'm in AZ) and everything seemed to be working fine at first - blower starts up, I hear some relays click, gas fires, and it starts blowing out hot air and heating the water - but then it stops after about 2 minutes and throws an AO code. Then it will sit there for 1-2 minutes, the code will clear, and it will start back up and go through the same cycle over and over. One time it stayed on for about 2 hours, but then the pump timer switched off, and when I turned it back on it started doing the same cycle over and over again. The troubleshooting guide says it's a bad vacuum switch, but I have tried a new switch as well as bypass that switch with a jumper, and it just does the same thing. I've also tried another circuit board but it didn't change anything.

Anyone have any ideas what else might be causing the AO error?
 
Did you try bypassing the switch with the new board in place? That should rule out a double failure.
I was going to suggest checking the tubing, but since you jumped the switch, that kinda rules that out. Did you get an AC error when you jumped the switch out?
 
I did check the tubing it it appears to be fine with no cracks and it is seated tightly at both ends. But like you said, if I'm bypassing the switch and it does the same thing then that rules out anything related to that switch entirely. And yes, I did also try jumping the switch after I put the new board in. What I do to simulate the way the switch works is start it with the switch completely disconnected (which would be the "NO" position), then once the blower starts I wait a few seconds and connect a jumper to the two wires (which closes the circuit showing that the vacuum switch has engaged), then the sound of the blower changes slightly and the ignitor starts up the flame. Then it'll run for 1-2 minutes and turn off with the AO code. So exactly the same results whether I use the switch or simulate it with a jumper wire.
 
That sounds like a flame ignition failure instead of a blower switch failure. I think I'd try cleaning the burner tube and igniter and all the connections between the igniter and the board and see if that helps.
 
If it were an ignition failure, wouldn't it just not light at all? It is lighting just fine and heat is coming out the exhaust vent nice and strong, but then it shuts off after 1-2 minutes. I haven't timed it exactly, but it seems to run for almost the exact same amount of time every time before the flame shuts off and it throws the AO code.
 
J,

I had a problem like this that drove me nuts on my Jandy gas heater. Finally pointed it as a bad connection on one of the sensors. I took them all off, cleaned them and treated with Corrosion Block. No problems since (been 2 years I think).

I hope this is helpful.

Chris
 
jleonard711 said:
If it were an ignition failure, wouldn't it just not light at all? It is lighting just fine and heat is coming out the exhaust vent nice and strong, but then it shuts off after 1-2 minutes. I haven't timed it exactly, but it seems to run for almost the exact same amount of time every time before the flame shuts off and it throws the AO code.
Click to expand...

I should have said flame sense failure instead of ignition failure. Once the flame is burning if the sense circuit fails to sense it, it will shut off the gas valve just like you're describing. Two minutes is just about enough time for everything to warm up and for any intermittent connection problem to open up. Chris may be on to something with his connection problem theory.
 
I thought about the flame sensor maybe failing and causing the flame to shut off, but when I tried the heater with the flame sensor disconnected it shut off within a few seconds after the flame ignited and gave me a different error code ("IF" I believe). I don't know if they simulates what a bad flame sensor would really cause, but I had kinda ruled that out as a result of my test. I may be wrong though. That was one of the few parts that wasn't replaced when I did the rebuild last year.
 
Usually if the flame sensor is going bad it will light, run a short period and then shut off. After three cycles like that, it would then produce a "IF" code on the display. Is there any change in the blower speed about the time this happens?
 
It never throws in IF code, even after cycling 20 times. The only time I got an IF code is when I ran it without the flame sensor, and then the flame only ran for a few seconds before going out.

As for as what happens when it shuts down, I hear a click and then hear the flame go off, then the blower shuts off for a second, then the blower back up and runs for a minute (I'm guessing as a "cool down" phase) while showing the AO code.
 

Enjoying this content?

Support TFP with a donation.

Give Support
ps0303 said:
Have you inspected the blower motor since this started? I know you said earlier you replaced not long ago.
Click to expand...
I thought it was last year that I replaced it, but looking at my Amazon purchase history it was actually a littler over 2 years ago - late 2016. And no, I haven't taken the motor out to inspect it because I figured there couldn't possible be anything wrong with it this quickly. But I suppose I could pull it check it out. Maybe I should test the resistance of the windings first according to the troubleshooting guide in the manual.
 
JamesW said:
Do you have a picture of the heater?

Is the heater leaking?
Click to expand...
No, nothing is leaking at all. I don't have a pictures at the moment, but nothing really to see other than the heater and its parts. Nothing is visually wrong that I can see at least.

I do have this video that I took, but of course when I shot this video was the ONE time that it kept running longer and didn't shut off until the pump timer turned off several hours later. If you notice at about the 1:25 mark I said I thought I heard the flame click off - which is usually around the time when it would turn off - but this time it actually kept going and the air coming out seemed to get hotter after that. So it's almost like there's something it is checking around that 1-minute mark which is normally failing and causing it to turn off, but this one time it kept going for some reason.

https://photos.app.goo.gl/2aNDr4fWcu5EetLi8
 
Since you replaced the circuit board and jumped the vacuum switch, there's not much else that can account for the AO error.

The only other thing that I can think of is maybe the wiring is bad.

Maybe try replacing the wiring.

If you have a good circuit board and a jumped switch, there's basically no way that you should get an AO error.

Check the heat exchanger for sooting. Maybe it's not allowing proper air flow.

Also, check that the input voltage is good and that the voltage selector plug matches the input voltage.
 
JamesW said:
Also, check that the input voltage is good and that the voltage selector plug matches the input voltage.
Click to expand...

You just mentioned something interesting about the voltage. The original motor I had in there was a 240V motor, and when I replaced that I went with the newer motor + main board combo which uses a 120V motor along with a new control board. However, I don't recall if I switched the voltage selector plug at the time when I swapped those out. But I do know that it has worked in the past since then, so that makes me think that I probably did. Or would it still work at 240V but maybe just cause premature blower failure, which is what I'm seeing right now? Maybe the blower is shutting down which is causing the vacuum switch to open and throw the AO code?
 
The voltage selector plug should match the input voltage.

If you replaced the blower with one that works on a different voltage, it might not be working properly.

Maybe check the voltage going to the blower.
 
Did you get part number IDXLBWR1930 for the blower?

I suspect that you probably got the wrong parts including the wrong blower and the wrong circuit board.
 
Last edited:
No, I got the blower kit IDXL2BWR1931 per Hayward's recommendation. The previous blower that I pulled out had a sticker on it which said 240V, however the new blower is a 120V blower - but it also came with a new control board due to the different voltage. This is a change they made in 2004, so the one that was in there before must have been the pre-2004 model.

I do have a 240V line running from the power control panel to the heater, so you're saying that selector plug should be at 240V regardless of what voltage the blower is?
 
The voltage selector plug needs to match the input voltage.

I think that you probably got the wrong parts.

The transformer converts the voltage from the input to the blower and low voltage depending on the plug selection.
 

Enjoying this content?

Support TFP with a donation.

Give Support
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply