I had this exact problem! Are the fans etc...not working at all or is it an intermittent fault?
I found the problem to be a loose earth. It was one of the earths behind the dash under the steering wheel on the right hand side. When i removed the lower part of the dash i think there were 4 earths with bolts holding all the wires on, one of the bolts had falled off and was in my foot well! Put it back on and it's been perfect ever since! If oyu are gooing to take a look at this yourdself you will need some torx drivers/bits to remove the lower dash!
Hope this helps mate!