I am replacing my heater core, unfortunatly, and I can figure out how to disconnect the lines that go from the ac to the heater core, I bought a tool even and it doesnt fit or somthing. if anyody knows an easy way itd be very helpful.
Do a Google search on Mustang heater core replacement. There are some online articles on how you can do the heater core replacement without disconnecting the AC lines. Somehow there is a way to loosen stuff up enough to get some slack in the lines that'll allow you to do the swap.