fan speed controller

i have a fan speed controller to run my room but the hygro meter is saying 18C but the fan speed controller has got a temperture override for the fans if it gets to hot but its set to 23c and the room is at 18c but the fans are staying on all the time i have to turn the override up to 28c to get them to turn off .

the tem probe for the over ride is under the lights by the plants is this the right place to have it or put it higher ??

i am unsure wat to do information please

It should not be in direct light. Preferably it should be at the height of the top of the plants (canopy height). Typically stuck to the wall by the wire or cord so that the sensor is in ir rather than touching the wall is most commonly done. It is good to actually have it inside an opaque box with small holes around the sides, top and bottom of the box. This will allow it to be at ambient air temp and not be heated by the light or cooled by fans. A simple small cardboard box, colored plastic bowl etc., with holes drilled/poked in it would work.

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