On Thu, 21 Mar 2013 21:56:49 +0000, mroberds wrote:

If the failure is that the blower motor doesn't run at all, they are
probably failing open. If the failure is either that the blower motor
runs at maximum speed, or a fuse blows, then they are probably failing
shorted.

Actually, I was remiss in not stating that the blower motor generally
fails by acting weirdly, often said to "have a mind of its own", and,
most often by a parasitic current draw overnight that kills the battery.