is my delica sick?

[almac]

so a few weeks ago i noticed some strange changes in my rpms after getting home from work.
symptoms:
1. when my AC is on, my RPMs drop about a hundred.
2. when i turn off my AC my RPMs raise about a hundred.
(i thought it was supposed to be the other way around; higher RPMs with AC on... )
3. yesterday i noticed that my RPMs increase slightly with the headlights turned off. i turn them on, and the RPMs drop slightly. my headlights are not dim at all(they are fine), and i'm not getting any kind of dash indication that something is wrong...

today i turned off everything "extra". no radio, no AC, no lights, etc. the van seems to idle a bit high (900) after a long hill, the van runs at normal temperatures.

are my headlights and AC too hard on my battery/charging system or something? i have a 6 light voltmeter/indicator, and it tells me everything is ok. other than an MP3 player adapter, and a ham radio, i don't have aything else drawing power while i drive.

i thought maybe the alternator brushes were getting worn.
should i be planning for an alternator or battery overhaul?

[FalcoColumbarius]

Almac, your idle should be at 750RPM, at least that is stock ~ not sure if you have customised it. 900 Is having pulled out of the car park and slowly accelerating from the car park, through the crowded school zone. Maybe your idle has something to do with it. Could it be that your A/C found more juice and had something to work with (grasping at straws)? How are your batteries, ampere wise?

Falco.

[almac]

i tried to load test my batteries, but i'm having a hard time getting my clamps under the hood safely.
i hope i dont have to take them out to test them.

[Fishtank]

Almac, there is an adjustment for the idle speed when you turn the AC on and off, quite easy to do, it only take a few minutes. I can't describe it to you since I drive an L400 now, and don't have a 300 diagram in front of me. Someone else on here should be able to give better directions and maybe a photo.