heater fan shuts off now and then?

["fluxmcfly" <bfreyguy@xxxx>]

Does anybody have an idea why my heater fan shuts off when running 
the ac.I'll have it on high then it with stop blowing or will blow on 
low,if you turn the fan switch to low then back to high it will work 
usauly.It does this quite a bit but not all the time.Could this be a 
bad switch or some type of power falure?Any thoughts would be 
appreciated 
very much thank you

Brian bfreyguy@xxxx