AC causing car to stall

I have been having problems with my car recently regarding the air conditioning. First it was that I would turn it on and nothing would come out. Pep Boys told me to get the condenser fan assembly replaced and because the AC switch was pushed in and would not push out, to replace that. I took it to my normal mechanic after ordering the parts myself. Since then, I get this moving water sound from behind the dash and I hear it when I start the car, make a turn or stop and when the AC is on and the car is idle, the car sputters and shakes and stalls with the battery and oil light coming on. I tried looking up the problem but all says different things. An auto parts store clerk tested the car and told me the alternator. A friend of mine that I trust said it needs a tune up with the spark plugs replaced and an air bubble is in the coolant and should replace the coolant. I have already spent near $1,000.00 to get this problem fixed and it is not. I do not want to spend anymore until I know what the problem is. What is the real problem with my car?