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My Hayward H400 pool heater is flashing the AO code. The blower motor is only running at maybe half speed and then it triggers the AO code without firing. Should I replace the blower motor or the vacuum switch first?

Posted by captjob on

  • captjob Sep 16, 2011

    Hi Daniel,
    Thank You. I will start with the switch and see of that fixes the problem. If not I guess I will replace the blower next. Thanks



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Daniel Scott

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AO is prover switch open error and is displayed if the blower prover switch opens unexpectedly during operation the control will shut down and attempt to re-light. If the switch does not close after the blower starts the control will go into lockout with the blower running. Replacing the vacuum switch usually solves the issue however, it is better to replace both the parts. Automatic reset is immediate after error is corrected. Hope this helps....please post back for further assistance.


Posted on Sep 16, 2011


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