Remove heater core

If it has a AC you have to pump down the AC remove the entire heater and AC unit so you can disconect AC lines and heater hoses ,you have to drop the steering column and remove the glove box, its a big job I would buy a manual so you know what all you have to disconect.

The heater core is located in the heater box, under the passenger side of the dash. Most FORD heater boxes are snap-clipped together, and if you remove the rear panel from the heater box, you will see the heater core...it looks like a smaller radiator...twist the heater hose off of the heater core (x2) from the engine side and gently remove the heater core from under the dash. When replacing the new heater core, be very careful re-installing new hoses to the core...it is a fragile thin metal that can leak almost instantly if tweaked too roughly...replace all parts in reverse order of removal.

Instructions

1. • 1Remove the dashboard. The heater core in S10s is behind the main dashboard, and it must be removed to access the core. The front dash panel can be removed by unbolting several screws at the bottom of the panel, then pulling the panel away from the dash. Once this front panel is off, the primary dash can be unbolted from the firewall with four large bolts below the windshield. Several accessories may need to be taken out to unbolt the dash from the firewall, such as the radio or 4WD switches.
   • 2 Drain the coolant from the core. There is a drain plug at the bottom right of the primary radiator that will empty the coolant system when unscrewed. Some residual coolant might remain in the core, but it will come out when the core is taken out
     
   • 3 Uncouple the core from the coolant lines. These hoses are directly behind the oil filler tube and will come loose when squeezed with pliers. They are of different sizes, and it won't be necessary to mark them for later re-attachment.
     
   • 4 Unbolt the core from its mounts behind the removed dash panel. Several bolts might be difficult to reach, but once free from the mounts, the core assembly slides up and out toward the interior of the truck. Lay a towel down when removing the core, as come coolant might splash out.
     
   • 5 Insert the new heater core and bolt it into the mounts. The openings will fit into the holes provided in the firewall.
     
   • 6 Reconnect the heater core hoses, and re-attach the dashboard and front panel.
     
   • 7 Fill the coolant system with a 50/50 mix of antifreeze and water. Tighten the drain plug on the radiator, then fill it. Crank the truck up with the heater system on its maximum setting and continue to pour coolant into the radiator until it will not take in any more.
     

Read more : http://www.ehow.com/how_5201441_change-heater-core-chevrolet-s10.html

Remove the glove box.On the passenger side under the hood, remove the two hoses connected to the heater core. remove the connectors/airlines connected to the box, remove the lever on top of the box.remove retaining screws. two screws hold cor in.-----------------------------------------------------------------
Car Diagnostic software

re-think that? remove glove box first and look again

Sometimes on really hot and humid days, the AC will make a steam like vapor out of your vents and/or defrosters, but most often this is caused by a heater core leak.

1981-87 Models

1. Disconnect battery ground cable.
2. Discharge A/C system and disconnect refrigerant and heater lines from unit.
3. Move shift levers away from dash.
4. Remove right side cowl trim panel, if equipped.
5. Remove 4 screws at base and remove glove box.
6. Remove brace through glove box opening and remove ashtray.
7. Remove right half of lower reinforcement (7 screws to instrument panel and 1 to cowl side of trim panel).
8. Disconnect radio ground strap.
9. Remove right upper air duct by removing mounting screw and pulling duct out through glove box opening.
10. Remove instrument panel center brace and right instrument panel cluster pivot bolt.
11. Remove instrument panel cluster, disconnect shift indicator cable and lower steering column.
12. Remove steering column studs and radio.
13. Remove scoop connecting heater to center distribution duct (2 screws).
14. Remove center distribution duct by pulling bottom of dash out to gain clearance.
15. Remove floor air distribution duct.
16. Disconnect temperature control cable through glove box.
17. Remove 7 retaining nuts from firewall and screw that retains assembly to cowl side sheet metal.
18. Flex dash out and remove heater assembly.
19. Remove nuts from door arms and remove door arms.
20. Remove 7 screws to remove cover from housing.
21. Remove evaporator core.
22. Reverse procedure to install.

try in the glove box area. may need to remove it too see the cover for heater core.

HI, not to long age i replaced my heater core in my 1991 Chevy S-10. Its not as hard as you mite think it would be, but its no a walk in the park.. :) There are a few things you need to remove. First the glove box door, ash tray, the panel that surrounds the stereo and stereo, also the tray that holds the ash tray and last inside the glove box there is a small plastic panel at the back remove that and that should do it if I remember right. Ok now the fun part, be prepared to get your hands a little bite beat up, you are going to need a lot of extension for your wratches, some antifreeze and lots of pattions also about three hours. Injoy Blake.

Just pull the dash back a little by undoing all the bolts and screws, its going to be a tight fit find someone with small hands.