1991 Plymouth Voyager heater core

Re- 1991 Plymouth Voyager 229,000 Km.
Recently I began to smell antifreeze very heavly inside the vehicle, and the windows began to get
coated with a foggy film. At first I was certain that the heater core had sprung a leak. However
after I checked the coolant level and found no significant loss and was unable to see any coolant
that had leaked onto the floor inside the cab. I went out and purchased a service manual for the
vehical and found that there are quite a few other controls at the heater proper. There is a Evaporator,
a Condensate dain tube, and a low pressure cut off switch. So before I begin taking the dash apart,
I would like to know if my problem could be caused by something other than the core itself?