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Thread: Jandy/Laars LX service help

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    Jandy/Laars LX service help

    I was wondering if there were any experienced people on here nice enough to help me with a question in regard to my heater. I turned it on for the first time this year to get the hot tub fired up. About an hour into heating, I noticed the temperature stopped going up. I checked the display on the unit and it was displaying the service code "ext sw 1".

    Google tells me I might be able to reset some manual switch, but I have no idea where to find it. Can anyone please point me in the right direction?

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Jandy/Laars LX service help

    That usually means there is something blocking the flue, causing an internal overheating switch to trigger. Typically, you need to partially disassemble the flue to clear the blockage, put it back together, and then manually reset the overheat detection switch next to the flue.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    In the Industry
    Pool Clown's Avatar
    Join Date
    Sep 2008
    Silicon Valley, CA

    Re: Jandy/Laars LX service help

    That error code also includes the fuseable link. This is a one time use (like a fuse) that needs to be replaced after you figure out what may have caused it to open.

    Possible causes are: What Jason noted and possible sooted heat exchanager, low gas pressure, down draft condition and or water flow problem. See areas outlined in pink to help remedy the ext sw 1 symptom.

    Please keep in mind, cause of this symptom must be addressed or corrected before resetting switch or replacing fuse as these are how the heater replys to a problem.

    IOW, the error "ext sw 1" is not your problem.

    If your heater actually says LAARS on it, the following may not be helpful.

    Flow charts courtesy of Zodiac Pool Systems, Inc.
    Factory Warranty Station for:
    Jandy/Zodiac, Pentair, Sta-Rite, Raypak, Polaris,
    and Paramount pool cleaning systems.

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