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Thread: Jandy LX400 heater Air Flow Fault Issues

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    Join Date
    Aug 2014
    Location
    Franklin, NC
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    7

    Question Jandy LX400 heater Air Flow Fault Issues

    Hello, I'd appreciate any advice on what to do.

    My LX400 won't stay lit - I'm starting up the pool for summer - it lights and then after the blower comes on it runs 30 seconds or so and shuts down with an Air Flow Error on the control panel. The blower runs fine, and the air flow switch tube looks good - so I replaced the airflow sensor. With the new sensor, the heater fails almost immediately after the blower starts up prior to the ignitor coming on - the ignition module flashes once indicating air flow fault. Huh? If I put the old air flow sensor back in, it purges, pre-heats, lights, blower runs, and it then stops and shows the air flow sensor fault on the control panel, not the ignition control. This is repeatable.

    I looked at the sensors and they both look the same. I tried cycling the heater looking with an ohmmeter across the NO contact to Common, but I don't see the switch operating when the blower runs. I would have thought that the switch would close during purge, so that the controller sees it and knows it is capable of closing - if it doesn't it should fault right away. It then should open when the blower turns off for the preheat and ignition, then close again when the blower comes on after lighting. If it doesn't see it close it would shut down and show the fault. No?

    In any case, I'm stuck. Maybe I have two bad sensors, but I would think they are so simple they would fail the same way. I'm assuming the system is working correctly since the blower runs fine and sounds like it always did. Do you think there is something in the flue? That is hard for me to get to so I haven't checked yet. Any other ideas or tips?

    Thanks so much!

    50000 gallon in ground pebbletech pool with spa and waterfall
    72sq" DE filter, Northstar 4025x30 pump on filter
    separate pumps on falls (2) and cleaner/SWG - all Northstar
    in floor cleaner, SWG, 400k Lx400 heater

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    Jul 2011
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    Re: Jandy LX400 heater Air Flow Fault Issues

    Take a look at the blower. Maybe a bad squirrel cage on it and that is why the replacement of the air flow switch didn't resolve the issue. Also, check the air tubes to make sure nothing has chewed on them.
    Paul
    http://www.gastekservices.com A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

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    Join Date
    Aug 2014
    Location
    Franklin, NC
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    7

    Re: Jandy LX400 heater Air Flow Fault Issues

    Thanks... I was hoping to avoid taking off the flue and the top, but I guess I'm at that point. The tube I replaced with the switch. One thing I wonder though, should I put some sort of lubricant on the tube at the blower nipple? It feels a bit too loose with the new (and old hose). Maybe it is not making a good seal, and that is affecting the pressure change the sensor sees?

    ...heather

    50000 gallon in ground pebbletech pool with spa and waterfall
    72sq" DE filter, Northstar 4025x30 pump on filter
    separate pumps on falls (2) and cleaner/SWG - all Northstar
    in floor cleaner, SWG, 400k Lx400 heater

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    FL
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    Re: Jandy LX400 heater Air Flow Fault Issues

    No need for anything on the tube. If the tube is what came with the new air switch, then it's the correct one from the manufacturer.
    Paul
    http://www.gastekservices.com A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

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