Error code AO defined as blower vaccum open

Dear ,

Please try the below solutions,

Solution 1:
If the blower prover switch does not close after the blower starts the control will stop the ignition trial go into lockout. The blower will continue to run. Automatic reset is immediate after the switch closes
Solution 2:
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. Automatic reset is immediate after error is corrected
Solution 3:
If the blower prover switch opens during the postpurge cycle (heater is not fir- ing) the control will display the error code. The post-purge cycle will be com- pleted once the blower prover switch close
Regards,
Samy

check gas pressure if not enough it will not run call gas company sounds like you need more pressure

The fan is not operating -- when this conditon exists, the unit will not fire up. Here's a link to the manual. The unit needs servicing.

http://www.hotwater.com/lit/im/com_gas/318556-000.pdf


Here are some excerpts from the manual relative to the blower prover and error msgs.

If the Blower Prover switch contacts do not close after the

Combustion Blower is energized the Control System will lock out and display Blower Prover Open

Blower Prover Open

Fault occurred 2 mins ago

The blower prover switch remains

open after the blower has been

energized.

Call a service professional:

Your Company Name Here

(press [DOWN] for more....)

These plastic sensing tubes must be routed to the correct sensing ports on the water heater. Sensing tube

routing should always be checked whenever Blower Prover Open, Blower Prover Failure, Blocked Air

Intake or Blocked Exhaust is displayed on the Control System LCD, see Figure 31 on page 29. These "Fault

Conditions" can be caused by incorrect sensing tube routing.

Charlie

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
stop the ignition trial go into lockout. The blower will continue to run. Automatic reset is immediate after the switch closes.Check to be sure combustion blower starts
If you don't have your manual you can download one for your exact model at : www.haywardnet.com

Check the tubing going from the blower to the blower vacuum switch. If there are any cracks, missing, or cut, it will give the same code. Rodents like to chew on this tube. Also, if the blower is not coming on at all, then you will get the same code, and the problem is not with the switch, it is likely in the blower.

The AO mindicates an open prover switch ,, here from Hawward site .
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. Automatic reset is
immediate after error is corrected.

If the blower prover switch does not close after the blower starts the control will
stop the ignition trial go into lockout. The blower will continue to run. Automatic
reset is immediate after the switch closes.

Check your wiring again on all the safety devices - Water pressure switch and both Hi- limits in the header.

Your problem then would be the pick up tubing and/or switch attached to the blower that closes once the blower is on to allow the heater to ignite. Pull the tubing and check it for dust or other debris clogging it and check inside the blower housing for the same. If you can test the switch under operation, you should see it remains open during start up which is why the burners won’t fire. If you do not find any obstruction (if you can, blow some compressed air thru too just to be sure) then you will need to replace the switch.

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.

http://74.125.95.132/search?q=cache:4mAdY7bLfoQJ:www.haywardnet.com/products/Manuals/pdfs/Manual227.pdf+hayward+AO+error&cd=7&hl=en&ct=clnk&gl=us