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The AO code came up when I tried to start the heater today. What does that mean?

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Is the blower coming on? If not, i would start with the blower. You would need to check for voltage going into the blower. If you do, and blower is not coming on, then the blower is bad. IF the blower is on, then check the tubing coming to/from the blower for breaks or disconnected. Also, may be a bad blower vacuum switch. You can jump this after a call for heat has been established to see if it fires. You should only attempt this if the blower is working.

Posted on May 19, 2010


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Can you run the pool heater with the AO code flashing

It will not run with AO code. That is telling you something is wrong/blocking the combustion fan from satisfying the safety switch. If it is a brand new heater this usually means the correct voltage has not been set in the heater = you would need to check what you have and then check setting. Doing this incorrectly could completely destroy all electronics in the heater.
If this is a heater startup for a new season the rubber tube from the combustion fan to the blower switch could be off or damage by rodent bites.
If this heater is older it could be a clogged heat exchanger which is a much bigger repair or problem for a homeowner.
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Ao error message in Hayward heaters

You didn't indicate exatctly which model you have. But on most the AO error code is :Blower vacuum switch
open error If the blower prover switch does not close after the blower starts the control will
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If you don't have your manual you can download one for your exact model at :

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AO error

This error is produced when the blower prover switch does not close after the blower starts, the control will stop the ignition and go into lockout. Automatic reset is immediate after the blower prover switch closes.

If you keep having this problem, contact a reputable service company, especially if it's under warranty.

The link to the owners manual is below, it references fault codes, etc..

Hope this helps.

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