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Thread: LT400 Laars heater - fan won't come on

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    Join Date
    Feb 2015
    Location
    Ft Worth, TX
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    2

    Question LT400 Laars heater - fan won't come on

    Greetings - I am trying to get my Laars LT400P-L pool heater going again. It used to work, but has not been used in 3-4 years (house rented out). The pool has been in use the whole time. When I turn on the heater (on spa or pool setting) nothing happens for about 2-1/2 minutes and then I get error lights "Service" and "air flow". The service diagnostic guide mentions the tubing - not an issue as fan won't come on. For fan not operating - it says correct the fault. I isolated the fan and put power on it and it works fine. What should I check next to see why the control circuit will not power up the fan?

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    JasonLion's Avatar
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    May 2007
    Location
    Silver Spring, MD
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    37,879

    Re: LT400 Laars heater - fan won't come on

    Welcome to TFP!

    It sounds like the next step is to track back the fan power and see where it fails. My guess is that there control board is sending power to the fan, but the wire is not intact, though that is just guessing. Animals sometimes nest inside heaters and chew up the wiring.
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    Join Date
    Feb 2015
    Location
    Ft Worth, TX
    Posts
    2

    Re: LT400 Laars heater - fan won't come on

    Quote Originally Posted by JasonLion View Post
    Welcome to TFP!

    It sounds like the next step is to track back the fan power and see where it fails. My guess is that there control board is sending power to the fan, but the wire is not intact, though that is just guessing. Animals sometimes nest inside heaters and chew up the wiring.


    Thank you for the welcome message! I checked the wiring for the motor and followed it back to the ignition controller (Fenwal) Not sure how to determine if the lack of fan power is because of a problem in the ignition controller itself or if the electronic controller is not telling the ignition controller to come on. Will have to sit out there with my meter and diagram and wrestle with it some more.

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