Nice write-up ujslost. :yesHeater core failure can be due to previous owner not using proper maintence. But usually its a failed part or electrolysis in the coolant system. From my experience of owning all differant brands of auto makes, seems fords are notorious for heater core issues.
I have to now put one in my 99 F150 apparently its stopped up. This time not leaking just not heating up.
What hose exactly? If the heater core burst/started leaking then yes you will have to do this. If the hose under the hood burst then you should be able to just replace it with out touching anything under the dash.Do I have to do this in order to put the hose back on? My hose burst, and the garage I used to go to just bypassed the heater core completely.