Heater Core: Service and Repair

Fig. 21 Heater assembly. Horizon, Omni, Charger & Turismo less A/C:

Horizon, Omni, Charger & Turismo
1. Disconnect battery ground cable, then drain cooling system.
2. Disconnect blower motor electrical connector, then remove ashtray.
3. Depress red color coded tab on end of temperature control cable, and pull control cable out of receiver on heater assembly.
4. Remove glove box and door assembly.
5. Disconnect heater hoses and plug heater core tube openings.
6. Remove two heater assembly to dash panel attaching nuts.
7. Disconnect blower resistor electrical connector, then remove heater support brace to instrument panel attaching screws.
8. Remove heater support bracket nut, then disconnect strap from plenum stud and lower heater assembly from under instrument panel.
9. Depress yellow color coded tab on end of mode door control cable out of receiver on heater assembly.
10. Move heater unit toward right side of vehicle, then out from under instrument panel.
11. Remove left heater outlet duct attaching screws, then the heater outlet duct.
12. Remove four blower motor mounting plate attaching screws, then the blower motor assembly.
13. Remove four outside air and defroster door cover attaching screws, then the door cover.
14. Remove defroster door assembly, then lift defroster door control rod out of heater assembly.
15. Remove 8 heater core cover attaching screws, then the core cover.
16. Slide heater core up and out of heater assembly.
17. Reverse procedure to install.

Fig. 23 Air conditioning & heater hose routing. Horizon, Omni, Charger & Turismo:

1982 - 83 Horizon, Omni, 1983 Charger & Turismo
1. Disconnect battery ground cable, then drain cooling system and discharge A/C system.
2. Disconnect heater hose at heater core. Plug heater core tube opening.
3. Disconnect vacuum lines at engine intake manifold and water valve.
4. Remove expansion valve ("H" valve) as follows:
a. Disconnect low pressure cut-off switch electrical connector, located on side of "H" valve.
b. Remove hex head bolt from center of plumbing sealing plate.
c. Pull refrigerant line assembly toward front of vehicle.
d. Remove two Allen head cap screws, then the disassembled valve.
5. Remove hose clamp, then the condensate drain tube from evaporator heater assembly.
6. Remove evaporator heater assembly to dash panel attaching nuts, then depress red color coded tab on end of temperature control cable and pull control cable out of receiver on heater assembly.
7. Remove glove box and door assembly, then disconnect vacuum harness from heater A/C control, located under instrument panel.
8. Disconnect blower motor electrical connector.
9. Remove right trim bezel to instrument panel attaching screws, then the right trim bezel.
10. Remove center distribution duct to instrument panel attaching screws, then the distribution duct.
11. Remove defroster duct adapter, then the panel support bracket.
12. Remove right side cowl lower panel, then the right side instrument panel pivot bracket screw.
13. Remove screws attaching lower instrument panel to steering column, then pull carpet from under evaporator heater assembly as far rearward as possible.

Fig. 24 Heater assembly. Horizon, Omni, Charger & Turismo with A/C:

14. Remove nut attaching evaporator heater assembly to plenum mounting brace and blower motor ground cable, then support heater assembly with hands and remove mounting brace from its stud.
15. Lift and pull evaporator heater assembly rearward to clear dash panel and liner. The panel will also have to be pulled rearward to allow assembly clearance.
16. Remove evaporator heater assembly from dash panel, taking care to prevent dash panel attaching studs from hanging up in dash liner.
17. Place evaporator assembly on workbench, then remove nut from mode door actuator arm on top cover.
18. Remove two retaining clips from front edge of cover, then the mode door actuator to cover attaching screws and mode door actuator.
19. Remove 15 heater assembly cover attaching screws, then lift cover door out of heater assembly.
20. Remove heater core tube retaining bracket attaching screw, then lift core from heater assembly.
21. Reverse procedure to install.