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Thread: Pentair Minimax 400 power LED only one lit

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    Join Date
    Jul 2008
    San Diego, CA

    Pentair Minimax 400 power LED only one lit

    We have a minimax 400 that we primarily use to heat our spa. My wife turned it on a few days ago and the water only warmed up to about 70*. I went to figure out what was going on and found that the only LED that was lit was the one for power. I have jumpered the hi limit switches, and the thermocouple without any luck or change in the LED lights. My next step is going to be ordering and replacing the thermostat circuit board. Is there anything else that I should check before I order this part?


    13,000 gallon inground gunite pool/spa. 2hp Whisperflow Pump, Pentair cartridge filter, Nature Soft SWG, Waterfall, Hayward Navigator.

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    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: Pentair Minimax 400 power LED only one lit

    Try killing all the power for ten seconds or so by throwing the circuit breakers. That's straightened out mine a few times. My display said Err and reverted to normal after that. If you do see it say something - mine says "LO" all the time right now because the water is below 55 - then read on.

    If the transparent plastic cover has fallen off, which mine did, the push pads on the control panel can get delaminated or something. Try wiggling your finger around when you push "pool" and see if things don't react. I've discovered that I can raise the desired temp no problem, but lowering it takes some finessing. I reattached the sun/rain cover so that no further damage occurs. The circuit board is pretty pricey.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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