[DutchmenSport]

You might have an excess amount of dust build up on the blower fan causing it to run slow, which will not allow enough air movement over the sail switch, thus causing the shut down.

Get a can of compressed air and blow everything around the fan and motor and make sure nothing is dragging it down. It takes only a tiny bit of collected dust, or a single hair to get would around and cause things to run slower. Blow everything out real good. It's a simple start that doesn't cost anything except some time and a can of compressed air. (or if you have an air compressor, use that... cost is then nothing).