This could be caused by one of three things
- No power to the unit - please check your power point is working where the system is plugged into
- Roof is too hot/cold (depending on season) to run - press the on button till your system shows 'flush' or 'on' to see if the fan starts running
- check your controller setting if you are in H (heating) or C (cooling) or HC
- Controller looks normal but nothing is happening
- Fan seized up for unknown reason.
If you are in doubt if its working or not then a quick and simple way of finding out is to turn the system to flush / ON mode (by pressing the power button) and then taking a tissue and hold it up to the vents in the ceiling, if you have more than 6 outlet you may have to try in different parts of the house as you have more than one fan and it could be only an issue with one of them rather than both.
If you have check all the above and the fan still won't run please leave system in 'off' mode and reply to your support email with your findings and we will contact you to give you a quote on replacing SCU or the fan.