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How To Replace Chevy Blazer Heater Core

The passenger compartment of the Chevy Blazer is heated by way of a coolant-heated radiator core that is mounted within the dashboard. It is possible for this core to get clogged, which can cause it to leak.


It is not complicated to replace the heater core and you can save yourself some major cash.

Tools and Supplies

  • Pliers
  • Drain pan
  • Vice grips
  • Coolant
  • Socket set
  • Screwdrivers

Here are the instructions:

  1. Take the front dash panel off. There are lower screws that need to be turned, and a single bolt holds the instrument cluster on. Remove the screws and the bolt and pull out the panel. Take off the switches to the rear wiper and the 4x4. If you lower the tilt wheel, you can get the entire panel off.
  2. Take out the radio, glove box and headlight switch module by unscrewing them.
  3. Unbolt the main dashboard in the front. You will see six to eight bolts that hold it in between the firewall and the windshield. Remove the bolts and carefully pull it away from the firewall without damaging the wiring harness.
  4. Next, you need to drain the coolant system. Unplug the drain plug and let the radiator drain into your drain pan. The plug is on the radiator’s lower left corner. Uncap the radiator to reduce pressure.
  5. Take the heater core hoses off the upper left side of the engine bay. You can pinch the hose clamps with pliers and pull them off. If the clamps have screws on them, just loosen the screws. If the hoses are stuck to the core nipples, then you can cut them off at the nipple while leaving enough hose to reconnect to the new core.
  6. The heater core is bolted down, so use a socket wrench to unbolt it. Once you have it unbolted, then move it towards the windshield and slide it out. Use a towel to clean up any spilled coolant.
  7. Replace the heater core and bolt it back into place.
  8. Connect the heater core hoses.
  9. Put the radiator drain plug back in and refill the system. Use a 50/50 mix of water and coolant.
  10. Put the dashboard back in and reconnect it to the firewall. Put all the dash equipment and switches back in place.
  11. Start your Chevy Blazer and add the coolant until the heater core is blowing hot air and filled.
  12. Put the radiator cap back on.

If you run into any trouble while replacing the heater core or replacing it does not work, then call your local Chevy dealer for assistance.