Greetings, I recently looked at heater core just right of gas pedal to check out as I have an occasional "antifreeze" odor coming from vents. I noticed that the bottom of assembly is plastic and on my heater core the antifreeze fluid is actually pooled on the bottom of the plastic casing . Shouldnt it only be carried thru heater core itself ???? and not be on the bottom of assembly. Is this core leaking??? Also is it possible that because Volvo brand antifreeze was not used when replaced by previous owner that the standard antifreeze is somehow reacting to the plastic and causing odor??? Thanks for help

Frank in south florida