Hi guys,
Wondering if any of you can help me with this problem .
90' 764 Turbo (b230FT engine), having an electrical problems.

symptom : WHEN THE OD Light is on, then all the electrical power like becomes so weak (ie. Power window / sunroof operates so slow ) . Then afterward (give about 20 mins or so ) it just stops the engine completely !
Tried to turn the ignition on, and nothing works.
Usually what I do, just wait for at LEAST an hour in a cold temperature weather or till the OD light dissapears. When that darn thing DISSAPEARS, then everything is back to normal again.

NOTE : when the weather gets hot, (bright sunny days 60 F or above ), the OD light usually lights up even before the engine gets warmed up.

I got so frustrated since my mechanic couldnt find the problem. VOLVO dealer didnt even bother to give me an assurance that they will fix this problem ( they said " WELL YOUR CAR IS AN OLD CAR so WE CANT PROMISE YOU THAT WE WILL FIX THIS PROBLEM !! " crock of _ _ _ _ !!!!
anyway, i took it to the Auto Zone, and let them check the Alternator/ voltage regulator and Battery. EVERYTHING SEEMS TO BE FINE ! OF COURSE when they DID THIS, the Darn OD light was NOT ON !!! :(

Please help me .. this is an extremely frustrating situation .

Thanks guys
Philadelphia, Pa , USA
90 764 T 165000 Miles
88 745 GLE 248000 Miles