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Fujitsu indoor fan stops when temp reached

deskdiver | Posted in General Questions on

Hello, we had Fujitsu ductless units installed few days ago (ASU24RLF, ASU9RLF1). Indoor unit’s fan stops completely on all 3 indoor units when temperature is reached. Does anyone know how to disable this and have the fan run nonstop? The manual specially mentions “The fan will operate at a very low setting during Monitor operation”.

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  1. monkeyman9 | | #1

    Hit the fan speed button til you get the speed you want and turns off auto (to quiet, low, med, high). Then the fan will always stay at that speed you selected. Otherwise, yes if the units are sized large enough that it can't modulate and run at their lowest setting then they will shut the fan off too.

    I generally run my Fujitsu heads on low or medium depending where they are. The Mitsubishi's heads Ive used run the same way. Just the 9 and 12k Mitsubishi heads modulate lower than the fujitsus do.

    1. deskdiver | | #2

      Thanks. Changing the fan mode to other than auto does make the fan run nonstop.

      It's odd how auto mode work differently than the manual suggested. Googling a bit more, manuals for other models mention there's a Fan Control function setting that you can pick between having the fan stop completely, or run at very low speed. Nothing in the manual supplied with my units.

      1. monkeyman9 | | #3

        There is a function chart for advanced settings. Never noticed that one but now you have me curious. I'll have to look later.
        I'd gladly have auto and use quiet mode instead of fan off.

  2. Kevin_Henry | | #4

    The way ours seem to work is that the fan runs all the time in Cooling mode with the fan set to a specific speed, but turns off at the set temperature with the fan set to Auto, or in Heating mode regardless of the fan setting.

    The manual I have implies (in its awkward way) this asymmetry between Heating and Cooling mode: "The Heating mode will not operate if the thermostat is set lower than the actual room temperature.... The Cooling and Dry modes will not operate if the thermostat is set higher than the actual room temperature (in Cooling mode, the fan alone will operate)."

    The manual also says something similar to what you quoted above about running at a very low speed during "monitor operation", but only in the description of Auto mode (that is, the mode where it switches between heating and cooling automatically based on the temperature). So I suppose you could try Auto mode, but "very low" speed may not be noticeably different from off.

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