My son bought a 2012 Avenger SXT Plus at auction. Car checks out great EXCEPT A/C not working. Recharged it and it lasts about 3 days then blows hot air. Mechanic checked, put in dye, and couldn't find a leak. Drove him nuts. Took it to a 2nd guy who works with A/Cs more. He checked it out, recharged it, added dye, watched it overnight. No leaks. Held a vacuum fine, ran for an hour with no issues, no apparent leaks. Kept it under positive pressure overnight, still no obvious issue. Said heater core is leaking and they're guessing there might be an issue in the evaporator, but that's a hunch. No obvious heater core signs (no coolant smell, no window fog, no coolant leak under dashboard, engine runs at right temp, coolant level is fine). It's also 100 degrees out, so no way to really check the heater! Damn expensive to replace heater core and evaporator - and of course don't want to do it if it's not needed. Avenger heater cores seem to be a common problem; any suggestions for verifying that it's the heater core and/or evaporator before tearing apart the dash to get to it? Anyone have anything that's worked for them?