Air condition problem

My friends are good, my car is 106, so the air conditioner of the car until 10 days ago was very cool, I said that I turned on the air conditioner, but the gas and maintenance was done 3 months ago. What is your sake to come to God, it doesn't cool like that. Would you help me? Thank you.

That whistling sound is coming because your vehicle's gas is stuck to the air conditioner