1992 AC Killing Battery

#1
Hey , so i'm new around here but thought i'd give it a shot. I recently bought a single owner toyota corolla 1992 for really cheap , from a friend. Car runs perfectly fine , and seems to have been taken really good care of . Recently the car battery has been dying and i bought a new battery, it was fine for around 3-4 weeks , and now it started dying again. Unaware of what the problem could be , and thinking it was my own stupidity of leaving things on , i finally got a multi-meter and tested the battery/alternator to see what the problem was. Battery was fine , Alternator was fine. Started doing the test by cutting things on one by one to see what was draining the battery and lo and behold it was the air conditioning . While on, it dropped the voltage from 14.2 while running to an easy 11.8 and that's without the other things on . My question is what can i do to fix the problem now that i know it's the air conditioning? I have an alternator that i bought , and a battery jump starter that's a good 220 dollars i could have back in my pocket but would rather be safe than sorry. Thanks in advance.
 
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