Constant Clicking noise.Exploding?
	
	
		My air conditioner/heater makes the usual rumbling noises that are pretty typical but... just about an hour ago it started to make a constant clicking noise.  One click every 7 seconds, like someone is tapping the inside of it.  What could this be?  I have tried everything from turning it off/up to kicking the thing.  Is this dangerous at all?  Its going to be Sunday so I'll have to wait till Monday to call, but what do I do until then?  Its driving me crazy and there seems to be nothing I can do.  I have absolutely no knowledge about these things.