97 GMC Safari Van 4.3 charging/alternator issues. 3rd alternator in one week.

[CHUCK06]

1997 GMC Safari Van 2wd 4.3 vortec v6. A/C front and rear condenser. Two weeks ago the alternator began to not charge, but only under a load. i.e. turning on the a/c. it would drop below 10v after 5-10 minutes of drive time. turn the a/c off and it would recover atleast to near 13v. So I replaced it friday with a reman from carqust. Started the van, not charging. Turned the headlights on and began to charge at over 14v. worked for a one hour commute then stopped. Would work intermittantly. exchanged alt. assuming it to have a faulty regulator. Installed second replacement. Started van with good and charged bat. worked great, next day did not work. Drove it this morning. was charging at 14v for a couple minutes then stopped charging again. Already tested battery connections and ground continuity, now im lost. 

[kev2]

  I would get out the test lamp and DVOM... see attachment si,ple system. ck the starter and fusiable link circuit,

  I have to add quality parts are so hard to get-  but 3 ?

I will ask about remote starter and ign switch as the 'L'  alt terminal would get ign on power...

[CHUCK06]

I have the battery on charge. I have not gone to pick the van up yet. But I had a post on her a while back conscerning a damaged starter mounting ear on the block that was broken. I that and replaced the starter. I'm thinking that maybe when I replaced the alternator, i may have tugged on the wire a bit causing it to loosen at the starter seloniod. I will check this when I go to pick it up. I think that is my likely scenario. Hoping so to say the least. Thanks for the diagram. I will keep you posted.

[CHUCK06]

also, no remote start system is installed on the vehicle.

[billr]

I think you are both right, it's a wiring problem and not a series of bad alternators.  That fusible link that is in series with the alternator output is what jumps out to me.  Kev2 (correctly) always asks about anti-theft and remote-start systems, but I think we can ignore them for this charging issue.

[CHUCK06]

Just got underneath the van for a look see. behold....lose connection at starter. must have pulled too hard on the cable when changing the alt. tightened and it's good now. Thank you again for your time and input.