Just wild speculation....but is there a chance that he overcharged it? Besides, why would an '06 need refrigerant anyway? My '02 with 95,000 miles and seven summer seasons has never been touched.
I think I'll make it another two months to get through this season, but am going to have to "recharge it" come Spring of 2009. Wal-Mart sells this stuff for less than $20 that is supposed to recharge any R134(a) automotive sytem.
Try using the "Tech" forum, as there may be some mechanics lurking there. Best of luck to you!!
2002 Sentra GXE in Molten Silver; 1.8L, 5-speed, Synergy Package. In 2012, it was repainted, had new struts installed, new head gasket, new water pump, new spark plugs, new sensors, and new belts & hoses. 150,000+ "original owner" miles.