A few years back, we ripped into an 87 Saleen Mustang to show our readers how to repair their own A/C system for their Fox Mustangs. Part of that repair was installing a new heater core because we had always believed in the adage that when you pull the HVAC case out of the car, you replace both the heater core and A/C evaporator core, as you dont want to do this job twice.
Recently, though, we talked with several shops that have replaced only the heater core (the more failure-prone of the two cores) without having to discharge the A/C system, making the job a true do-it-yourself repair you can complete at home. We decided to attempt the task ourselves and see what the outcome would be, and if it was truly worth the savings of not having the A/C system purged and then recharged, which averages about $100.
Basic metric handtools, a T-20 Torx driver (or bit), a Phillips head screwdriver, a large flat-blade screwdriver (or small prybar), and metric combination wrenches should be all you need. If you can, get a friend to help, as there are a few steps that go much easier with an additional set of hands. Also, you might want a few lengths of some 2x4s to hold the dash out of the way if you are going solo.