I think my heater core is just starting to leak.I get a antifreeze smell inside the van about once every 7- 10 days and then it goes away. The smell goes away in less than a half a day. Nothing wet yet like rug or heater box. Does the ac have to be pulled to replace the core? I've done other cars before and it was just taking time and being careful. Do aftermarket heater cores work ok or is dealer better? Thanks for any info.