97 E320 W210, 155K miles. Brand new battery, alternator was new Bosch replaced about 1 year ago. Battery & alternator tested fine a couple weeks ago.

As soon as A/C is switched on, the dash, dome, and headlights flicker as if the voltage regulator or alternator is shot. If driven long enough, the battery will drain completely as indicated by failure to crank and start after it is shut off.

If vehicle is driven without A/C engaged, none of these problems is experienced and the car starts fine each time without any problems.

Any ideas?

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