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?
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?