Today for the first time I noticed under hard accelaration my AC fan would die down and almost quit, then when my speed leveled out it would resume normal blowing speed. Is this the sign of a weak alternator? I have no other electrical complaints otherwise.

Could the A/C or Alternator belt(s) be just loose enough to slip only higher RPMS?

  I did tighten the belts but did not do a road test, I will this morning. It is dark when I go to work and I must use my headlights. I will run both AC fan and lights for a test and I'll post the results when I get home this afternoon. If I still get a drop I'm going by the auto parts store for a bench test.

  My unofficial road test this morning showed no loss of headlight brightness, still my AC dash vent flow decreased to nothing however, I noticed continued air flow at my feet so, my conclusion is a vacuum leak that deprives the dash actuator under hard acceleration.

I was thinking the same thing...belt may be loose enough to cause that. They will usually make some kind of noise if that loose, but not always.
It may be time for a new alt, or a rebuild on yours. The brushes in the alt could be worn enough the bounce, or not make good contact at higher rpms. Let us know if tightening the belt helped.


Dang...your fingers are faster than mine!!

Now it does sound more like a vacuum issue...the fan is blowing properly, but the airflow is being re-routed....definitely a vac. problem. Your vac. reservoir may have a leak, or a line to it has sprung a leak.
When you get on the gas hard, vac drops to almost nothing, so you need a reservoir to keep all of the vac. operated stuff working. If there is no reserve, then when the vac. drops, the vac. servos(for the HVAC) will "default" to whatever position "off" is. Adams' Apple2008-07-16 05:06:10

  You are correct, the auto parts store checked and the alternator is producing god voltage and amperage, he also said the vacuum drop would shut down the air flow to whatever position the default is, he thought it was the defroster on most vehicles.