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17 years GM tech
17 years GM tech, GM master tech
Category: Chevy
Satisfied Customers: 1918
Experience:  25 years automotive experience, 15 years with Saturn
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change the heater core on my 1977 chev.

Resolved Question:

I need to change the heater core on my 1977 chev. c20 truck.
Where can I get instructions.
Submitted: 6 years ago.
Category: Chevy
Expert:  17 years GM tech replied 6 years ago.

17 years GM tech :

Hello and thank you for your post. I am a master certified GM tech and can help you to resolve your issue.

17 years GM tech :

these instructions are for a 1982 and might be the same. You have to look and see.

17 years GM tech :
  • Disconnect battery ground cable, then drain cooling system.

  • Disconnect heater hoses at core, then plug core tubes to prevent coolant spillage.

  • Working from engine compartment, remove distributor duct stud attaching nuts.

  • Remove glove box and door assembly.

  • Disconnect air-defrost and temperature door cables.

  • Remove floor outlet, then the defroster duct to heater distributor duct attaching screw.

  • Remove heater distributor to dash panel attaching screws, Fig. 23.

  • Pull distributor rearward, then disconnect all harnesses that will interfere with distributor removal.

  • Remove heater distributor from vehicle.

  • Remove heater core retaining straps, then the heater core.

  • Reverse procedure to install
  • 17 years GM tech :

    if you have a/c as well...

    17 years GM tech :

    With A/C



    1. Disconnect battery ground cable, then drain cooling system.

    2. Disconnect heater hoses at core and plug core tubes.

    3. Remove glove box assembly.

    4. Remove screws at center duct to selector duct/instrument panel. Remove center upper and lower ducts.

    5. Disconnect bowden cable at temperature door.

    6. Remove nuts at selector duct studs (projecting through firewall). Remove selector duct to firewall screw.

    7. Draw selector duct assembly rearward so core tubes clear firewall. Lower assembly sufficiently to remove vacuum lines and harness connections.

    8. Remove selector duct assembly. Disconnect core mounting straps and remove core, Fig. 24.

    9. Reverse procedure to install.

    17 years GM tech :

    hope this helps

    17 years GM tech and other Chevy Specialists are ready to help you