Yes thanks I'll get up under the dash and see what's going on. I think you're referring to that vacuum activated 4 way valve in the engine compartment involving the heater hose. Had to replace the Oreilly's version twice in 10 years as it keeps cracking and losing coolant. Would a leak there show up as a smell in the cabin somehow?
Is 'core' the radiator itself? I think that radiator is only a couple years old so I'm guessing it should be ok. I've always kept fresh coolant in it. Or are you referring to if the heater core was blocked? Would that cause it to change how coolant flows at the rad cap?