Nissan Repair: engine stalling, sentra model, nissan sentra

Question
i got 2 questions:
-why my engine stalls whenever i swicth on my air-con,only when idling? i need to increase the idle speed to expect no engine stalling,but the idle is too high when i switch it off.what's wrong?
-my 2nd question,maybe related to the first- when you accelerate, i can hear a loud hamming sound,only when my air-con system is switch on.it disappears once air-con turns off.what's this?
MY CAR IS NISSAN SENTRA,MODEL 1997.


Answer
Sonny,

It sounds like your airconditioner is failing and the compressor is soon to go out.  I would have the compressor checked before it breaks.  If it locks up it will throw the belt.  Since you say the car runs fine with it off the compressor clutch is working fine.  So, take your car to a shop if you cannot replace the compressor yourself.  What they will do is replace the compressor and receiver dryer and recharge the system.  You should be fine after that.  I would not run the airconditioning until it is fixed due to the fact if the compressor belt is thrown it might take another belt out with it or it might drive something else besides the airconditioner compressor.