Repeated APPS failure
 

The APPS on my truck is on the fritz for the third time in the last 5 years with only 33k miles driven in that time. Most of the miles have been city miles. I replaced the part about 3 years ago and also installed the "noise" reducer at the same time thinking that maybe I was getting interference from the alternator. Well, that didn't really help as here we are again. So, a couple things that I have noticed and am now wondering if they are related.

RPMs dip on the truck while idling. It will drop for one second and then return to normal. It will continue to do this every 30 seconds while at idle. Not normal, right?

Headlights will go dim and then brighter when this happens. More pronounced when the truck is colder.

I have never been able to adjust the volts on a new APPS. I have tried everything under the sun with each new one that I have put in and no luck.

Anyone have any ideas why this might be happening? Any ghosts that I can chase to try and get to the root of this?

Sounds about like the interval of the a/c compressor cutting off and on, that would explain the rpm drop and voltage fluctuations. Compressor clutch magnet going bad drawing more juice?