heater blower motor only works once in awhile it acts like a lose connection but

trust your first instinct anything intermittent is exactly that something loose a wire a connection that's bad somewhere check from fuse box to fan and guarantee you'll find it. Also clean any sensors such as door sensors etc. Make sure they are connected well and im sure your intermitent prob wil go away. P.S.sometimes taking a pair of needlenose to squeeze the connectors just a tiny tiny bit helps to keep this prob. Away for good knock o mn wood.