Fan speed controller

[the pict]

This seems a straight forward control, however the fan runs very slow and it does adjust speed when the dial is turned down, so by taking the controller out of circuit the fan should run at full speed ??, does anyone know if this is a current or potential control, I am sure its a Vent Axia as its has "Roof Units" on the front cover,
Ta P

 

[Lucien Nunes]

These are normally phase-angle controls similar to hard-fired lighting dimmers. The fan will run at full speed with the controller bypassed. Some fans use a 3-wire connection to the controller so that the capacitor winding is not phase-angle controlled, it receives direct mains. If that applies to this fan, parallel the two windings; e.g. if the controller has outputs L, N1 & N2, take a neutral to N1 & N2. As a double-check the controller will drive a tungsten lamp happily.