well i was experiencing the same issue a couple of months ago but not as often and it didnt matter whether the lights were on or heat. it did it at all times. then my timing belt broke, did some damage, and a mechanic fixed everything by replacing all of the damaged parts plus some inside of the engine. when i got it back it was perfect. no surging, nothing at all. then my alternator failed a day after and then i had it changed with a used one. still the car was perfect no problems for two weeks all until the A/C button was pushed. that is when the problem began and hasnt stopped since. so getting the alternator tested will tell me if is the alternator, correct? would there be anything else that it might be? thank you very much for your help.

AJ