Blower unit

I have had my Disco for a while now and the blower on the heater has been giving me a bit of a problem. When I start the car for the 1st time the blower starts to blow air out, but after a few minutes it just stops then once I have driven for about 10-15 minutes the blower comes back on, any idea what I should be looking for and could be a short in the electrical system and if so where do I look for it.

ive noticed when the engine is hot the blower shuts down for a few mins then starts again. i thought it might be a temp sensor built into the heater ?