No air coming through cabin vents

I have a 2010 C4GP and just discovered that no air is coming through any of the air vents even with the fan set to max. I have checked all related fuses and they are fine. I dont know if this is just coincidence but i removed those pesky drain plugs last week as they were bunged up but i dont see how that could have affected anything. I have read something about a resistor block failing, could somebody point me in the right direction about how to check/replace that as i guess its the next logical step? If the fan motor is shot is that expensive and is it possible to diy or does it need a garage?
Is the fan assembly/motor behind the dash or in the scuttle area?