1998 Chevy S-10 Blazer Heater Core Removal

A malfunctioning heater core on your Chevy Blazer will cause your heater to blow no warm air and will likely cause coolant to leak into your passenger compartment. If this happens, you must replace the core. Unlike older models of the Blazer, you have to completely remove the heating/ventilation module from the 1998 truck to change the heater core. This work is in addition to removing the dashboard to access the module.

Instructions

Remove the Dashboard

1

Disconnect the negative battery cable. Drain the engine coolant into a large container, removing the drain fitting at the radiator and then at the engine block. You may need pliers.

2

Loosen the hose clamps on the heater hoses with pliers and disconnect the hoses from the engine-side firewall. Plug the open fittings; rubber plugs work best.

3

Disconnect the two lower dash trim panels, unscrewing them with a screwdriver and then prying off the clips.

4

Remove the vertical bolts at the bottom of each end of the dashboard -- a ratchet wrench with an extension will make this easier -- and then remove the Torx screws at each bracket with a Torx driver.

5

Remove the nuts for the steering column with a wrench and lower the column. Remove the single bolt near the center of the dashboard. It is located below a vent. Pry off the upper speaker and defroster grilles and remove the bolts beneath them.

6

Grab hold of the dashboard and pivot it downward, disconnecting and electrical connectors and cables behind it. Pull the dashboard out of the truck.

Remove the Heater Core

7

Label and disconnect all of the electrical and vacuum connectors on the heating/ventilation module.

8

Disconnect the electrical connector on the blower motor resistor. Cut along the square outline of the resistor with a sharp utility knife. Remove the resistor from the housing.

9

Unscrew and remove the single engine-side bolt for the module with a ratchet with an extension and a flashlight for better vision. You must use this same bolt at this same location for the reinstallation.

10

Remove the module's nuts and bolts on the passenger compartment side and remove the heating/ventilation module.

11

Unscrew and remove the heater core cover and slide the heater core out of the module.

Install the Heater Core

12

Slide the replacement heater core into the heating/ventilation unit and close the cover with the screws.

13

Install the module back into the truck with the screws, including the single shorter screw that must go on the engine side. Reconnect all of the electrical/vacuum connectors.

14

Reconnect the blower motor resistor by gluing it in place with black weather stripping adhesive and its electrical connector.

15

Reinstall the dashboard with bolts and fasteners. Reconnect the grilles on the dashboard and the lower trim panels.

16

Reconnect the heater hoses at the firewall.

17

Refill the radiator with the engine coolant with new water and coolant if the original mixture is contaminated.

18

Reconnect the battery cable.