I plan on replacing my alt this spring, maybe with 136 amps. Currently if I'm running at night with the blower on high and I slow down my blower slows momentarily as well.

Aren't alternators designed to put out the same voltage/amps at all RPM
ranges? Since my blower motor slows when the RPM's subside, is that a sign that my alternator is on it's way out?

Brand new battery this fall.

Thanks.

 

Alternators put out the same amps when they've reach operating rpm range. 1500-5000 RPMs may not make a difference in output, but 600-1000 RPMs certainly can. What's drawing on it can make a huge impact as well. Headlights, fogs, wiped blades, a/c cranked to max, stereo booming, and trying to charges laptop, is a far more significant draw than a 72* day with the windows down.