Battery Over Charged-COntinued
 

I have followed the "Spewing Battery!" thread and the "Battery Venting Cloud of Hot Acid" threads and still have a question. I have a 1978 W123 280E with 45,000(really!). I get battery overcharge characteristics ONLY when I run long and hard with the compressor on. I have a new battery, because I cooked the old one I have replaced the voltage regulator and get ~13 volts with a meter at idle and with compressor on at idle.

My question is this. What is the relationship between the compressor and the alternator? Why should I get overcharge only when the compressor is on?I get good air-co when the the compressor blows. The compressor seems to come on and go off as needed.

Any thoughts or good suggestions for further diagnosis?

Thanks, Alex

Replaced Regulator
 

Thanks for your suggestion. I put in a new regulator about a month ago to resolve issues of unexpected dimming headlights, poor restarting performance and overcharging battery.

I thought I had it licked, but problems still continue. Occasionally, when starting after driving, I get a whole lot of cranking with no fire. Eventually it will start, though many a tense moment as my wife is again about to ask "why did you get this car?" The unexpected dimming of the headlights has been resolved. In addition to new battery, I have new plugs and wires.

The regulator I took out when replacing with a new one looked pretty good. It's "brushes" still had a good 3/8" to 5/8" left othem, so I put it on the shelf.