Given the other tests have failed, I'm leaning towards the fact that it could be the heater core. Question is, how will the dealer confirm this ? I don't want to pay them hours of labor just to diagnose this. and Given it's -15 degrees here in NJ these days with the wind chill factor, I don't want to induldge in doing this myself at the moment either
At worst case if it is the heater core, I've read posts where the labor charges are 18 hours to replace this and the heater core itself being 900 or so... is that correct ?