How to replace heatercore in 1985 GMC vandura?

Answer 1

This takes time, patience and usually causes a lot of swearing. If you look on the passenger side below the dash there is a black curved box, the heater core is in there so that whole black box must be removed ....

Removing it involves removing all the screws holding the dash molding down, you have to remove the dash support bar on the passenger side, disconnect all the ducts and disconnect the hoses from under the hood (there are two and they are just below the AC system and go to the firewall.) Since the heater core uses engine coolant it's best to drain the radiator first (perfect time to do a flush as well!). You might also need a gentle application of force with a pry bar to get it out.

All in all, swapping the core in the black box takes about 5-10 minutes, getting the box in and out of the vehicle takes hours.