Disco TD5 heater problem

Good morning all,
Well I picked up my new disco yesterday and she's already playing up (not in a major way) after driving round having a bit of a play I noticed my blowers wernt working. I had a good half hour trawling through previous threads on here but I can't find what I'm looking for. I've got a manual blower switch on my disco but all the other advices is for the digital blowers.
The main problem I'm having is the blowers work when they feel like it. I have checked the fuses and there ok but I'm not sure how to check the switch etc.
If anyone can give me some advice I'd really appreciate it. I'm not sure if I've been looking for the wrong thing.
Many thanks
Rob

What do you mean with manual blower switch?

Sorry about the terminology, instead of a LCD display there's a manual sliding lever to select the blower speed and two heat selector dials and one directional dial. Hope this makes sense

Right bit of an update. Just been out and went over a speed hump and low and behold the heater has come on. Im guessing I have a loose wire or connection somewhere. At least its given me something to look at. Feel a bit better now as I know the heater blower works.