BMW: 2000 bmw 328 ci A/C not cooling, r 134a refrigerant, bmw 328 ci

Question
Thank you mr. roberts. i did take the car to the mechanic and they recharged the freon which got the A/C to cool; however a day after i was in the same situation. i no longer have any cold air coming out. i notice that the air on the passenger side feels to be a little bit warmer than on the driver side. can you advice, i dont want to get ripped off when i go to the mechanic. what can be the problem and how much is it goint to cost me. thank you again.
PS: no refrigerant smell inside the car.
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Follow up To

Question -
Hello Mr. Roberts, I have a 2000 BMW 328 ci with about 97,000 miles on it; Just bought it about a month ago. When I first bough the vehicle the A/C was cooling perfectly, too cold i would say, but as weeks when by, it statted to cool less. At one poin, it would only cool when i was running in the freeway, but it wouldn't cool when fully stopped. Now it is not cooling at all. Please advice, does the car take freon or can something else be the issue. thank you in advanse.

Answer -
Josh,
The a/c compressor isn't turning on because of a low freon charge. The pressure sensor told it to shut off because it didn't want the compressor to hurt itself. Two places to look for a leak. The a/c service fitting on the passenger side of the radiator at the front radiator cowl (this is the high side fitting) or the expansion valve. If it were the expansion valve you would have had a refrigerant smell in the car though. The pin in the service valve leaks at the seal. Replace the entinre valve. It should be $30-$40 at the dealer. All it takes is a 17mm and a 19mm wrench. Just be aware that any residual pressure in the system will blow out with high pressure when you take the valve off and that is against EPA regulations. My best tip would be to take the valve you buy at the parts counter to an a/c service shop of your choice and let them change it and refill the system. It is r-134a refrigerant and it takes 1.63lbs to fill. Good luck.

Answer
Josh,
Please read my previous advise. I virtually told you where the leak was and how much the part is. Almost all refrigerant oils come with UV light reactive dyes to pinopint leaks. The shop you had refill it should be able to find any leak now and if they tell you they can't then they suck and they don't know BMW's. If this is the case spend the extra money for a reputable shop, a more quality repair now saves you money down the road since you won't have to pay over and over again. Please read my original response. Thank you.