Has the same mechanic done all three repairs? Maybe he's not putting enough oil back in the compressor. Did he change the orifice tube? If not, the tube may be blocked. Did he change the drier/accumulator? Be sure that when you replace the compressor, you also change the other two parts previously mentioned or the warranty on the compressor will be invalid. Its also wise to change all three parts when one breaks. I replaced all three parts on mine two years ago on a 2007 Tahoe at 150,000 miles and have not had any problems. I put in a Denso 471-0316. I did the repairs. Good luck. Hope you get it working.