another heater question
 

I've noticed others have this problem, but I haven't found yet the answer.

What would make my blower stop completely? It's sporadic...driving on the interstate, heating fine...then just quits for a few minutes...then click, starts up again. I notice it more when the fan speed is slower....all buttons work, when heating, the air is HOT. Occasionally the air will get cold for a few minutes then warm up again...aux pump working (probably the monovalve) but I just want to know why it stops. Has blown 2 fuses already...car 15 years old. If the blower motor is known to draw more current as it gets older, could a larger fuse be used rather than bypassing with an inline fuse? Don't want to fry anything but it's aggravating to be driving with the fan in 3rd speed, and turn on the signal for that extra current draw momentarily and poof the fuse shoots. Both times the fan speed was in 3 or 4 position. Sorry this is long...I'm sleepy.;)