Air cooling

My car is Lexus, RX350, 2008 and this is the VIN: 2T2HK31U58C062894 I have a problem in the air cooling and heating where the air comes out normally but without cooling in summer or heating in winter, besides, that when the air conditioning comes out it comes from the right cooler than in the left side, and for the heating it comes heater from the left side than the right side. I though in the beginning that this is maybe a gas air conditioning problem, so I went to fill the gas and after that everything was ok, then after 1 week everything turned to be exactly like before, so I went to a mechanic he told me that I need to fill it with a laser gas so he can find the source of the air leakage, I did that and I came to back to him after the gas finished, he told me that there is not leaking in the compressor and it is must be ( we call it in Arab countries the air condition refrigerator or fridge) (I don't know guys what do call this part in car wise, it is the part that cool and heat) anyway, they told me that I have to change it totally because it cant be fixed Please advise