Fan Control with Slic3r issue

I have hooked up a 12v fan to my Melzi fan control.
I can turn it on and off with M106 S255 / M07 without a problem.
I have enabled fan control in Slic3r, but the fan never comes on during a print.

Any suggestions?

Thanks
Phil

Not all fans work for the whole control range. One fan I have works from 75 to 255 while another only starts up for values greater than 200. Try setting the minimum fan speed in slic3r to 250 and see if it comes on then. Slicer will only turn the fan on if the layer print time is below the specified threshold. The only thing that will be guaranteed to bring the fan on is bridging.

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Using ABSPrusa Mendel Zaphod with Pronterface and slic3r 1.3.0. Printing well with 3mm PLA and ABS through 2 x J Head Mk IV b and Wade Geared Exruders. Controlled using RAMPS1.4 board running Marlin_v1.1.9

MotoBarsteward,

Thanks.
I started at 255 and worked my way down until the fan stopped working (about 120) and used that for my min setting :-)
All working now.

Phil