It is possible to replace the heatercore in earlier cherokees without discharging the A/C.
I am in the process of replacing my heatercore on my 1990 as I type this.
Follow the standard procedure: Remove blower fan, remove underdash, unplug all the wires/cables/vac lines. Remove the 3 firewall nuts that hold the whole assembly together, remove the heater hoses, remove the BRACKETS and whatnot that hold the a/c lines.
This is where things change a bit, remove the two large dash bolts on either side of the dash that go into the a-pillar, then loosen the 2 large nuts that hold the steering column to the kneebar almost all the way off.
I used an adjustable hoodprop to hold the dash up, but basically you can now pull the dash up almost 4-6" and prop it there. Grab the whole black plastic assembly and pull it back, the main holdup I had was the metal block looking thing on the a/c lines, it took me pushing from the outside for that to clear the firewall lip and slip inside. you can get the whole assembly about 4-6" back from the firewall, then rotate it counterclockwise so the inner(heatercore) end drops 6-8" or so. Then remove the two retaining screws for the heater core, and slide it out over the top of the whole assembly and rotate it clockwise so the inlet/outlet tubes clear the dash.
Aside from the adjustable hoodprop (snapon FTW), another tool that made this job MUCH easier was a 16" flexible handdriver Snapon part number TM615. Having this long flexy bastard to get to all the random nuts and screws made things WAYYY easier.
Took me about an hour maybe an hour and a half to get the core out with this method.
Hope this helps, draining the R12 is a pain in the ass.
:guitar:
I am in the process of replacing my heatercore on my 1990 as I type this.
Follow the standard procedure: Remove blower fan, remove underdash, unplug all the wires/cables/vac lines. Remove the 3 firewall nuts that hold the whole assembly together, remove the heater hoses, remove the BRACKETS and whatnot that hold the a/c lines.
This is where things change a bit, remove the two large dash bolts on either side of the dash that go into the a-pillar, then loosen the 2 large nuts that hold the steering column to the kneebar almost all the way off.
I used an adjustable hoodprop to hold the dash up, but basically you can now pull the dash up almost 4-6" and prop it there. Grab the whole black plastic assembly and pull it back, the main holdup I had was the metal block looking thing on the a/c lines, it took me pushing from the outside for that to clear the firewall lip and slip inside. you can get the whole assembly about 4-6" back from the firewall, then rotate it counterclockwise so the inner(heatercore) end drops 6-8" or so. Then remove the two retaining screws for the heater core, and slide it out over the top of the whole assembly and rotate it clockwise so the inlet/outlet tubes clear the dash.
Aside from the adjustable hoodprop (snapon FTW), another tool that made this job MUCH easier was a 16" flexible handdriver Snapon part number TM615. Having this long flexy bastard to get to all the random nuts and screws made things WAYYY easier.
Took me about an hour maybe an hour and a half to get the core out with this method.
Hope this helps, draining the R12 is a pain in the ass.
:guitar: