I guess heater core is out again, my son in law replaced it about 5 months ago but now windows fogging up and humid inside. I did not watch him do it and now we are not speaking so, is it hard to replace? 94 F-250 5.8

 

If I understood my Chilton Manual correctly. Basically remove the glove box There should be a panel with screws. Remove screws remove heater hoses There may be a bracket that holds the core in.
I know my 86 F250 was this way. On my 95 I haven't looked to see but I'm 500 miles away from it so can't look. This is on factory A/C models. I use to change my 86 heater core in about 20 minutes. But buy a good one. pay the extra for a NAPA, CarQuest,etc.
Craig

 

Thank for the info, the last one came from Auto-zone, guess that is the problem.