How to Replace the Heater Core in a 2000 Chevy Blazer

Heater vent

The 2000 Chevrolet Blazer heater core is a commonly replaced part of the heating and cooling system, due to problems with its placement and design. When the car is sitting level, debris is drawn to the core because it is the lowest point in the engine cooling system. After repeated debris deposits collect there, it will plug and either leak or stop functioning. The average backyard mechanic can replace the heater core in the 2000 Blazer in about four hours.

Things You'll Need

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

Instructions

1. Disconnect the battery by turning the positive terminal bolt counter-clockwise. Stow the terminal wire away from the battery.

2. Locate the heater core's hoses on the passenger' side firewall of the engine compartment, and remove them. They are held in place with hose clamps, which have small screws that can be turned counter-clockwise to loosen the tension. Usually, the hoses have become stuck to the heater core's nipples due to the heat, and they can be twisted off with pliers or simply cut. They are sized only for the nipple they are designed for, and the top hose is the heater core's input. The bottom hose is the return. Disconnecting these hoses at the heater core will spill coolant down the firewall; aim the open hoses at the drain pan below and allow the coolant to drain out. The 4.3 liter V-6 in the 2000 Blazer has enough room to allow drainage from this point, but it should be done with a cold motor. Wrap the open hoses with a towel and lay them aside, pointing upwards.

3. Remove the dashboard to gain access to the heater core from the interior. This needs to be done in pieces. First, turn the bolts on the underside of the kick panel counter-clockwise, then remove the single screw on the underside of the gauge cluster. Pull the front dash panel cover gently from the upper right corner to disengage the clips, then pull evenly on the rest of the panel to release the rest of them. Slide the cover over the steering column and stow it in a safe location.

4. Remove all of the "pull out" switches and trays, which include the rear wiper switch, 4x4 switch assembly, glove box, and ash tray (pulling the adapter plug apart where required).

5. Remove the radio by turning the mount screws counter-clockwise and pulling the radio directly out. Unplug it form the wiring harness by pulling the adapter plug from the rear of the radio body.

6. Remove the gauge cluster and headlight switch assembly by turning the bolts counter-clockwise and pulling them directly out of the dash. The air conditioning controls can remain in place.

7. Remove the large bolts between the windshield and the dash board by turning them counter-clockwise. The dash will become looser with each bolt that is taken out. Once the bolts are out, pull the dash gently until it has about a foot gap on the passenger's side. The steering wheel can be placed in the lowest tilt position to allow the maximum gap on the passenger's side.

8. Remove the heater core behind the dash by turning the mount bolts counter-clockwise and pulling the unit up into the passenger compartment. The nipples will protrude through the firewall, and removal could be tricky. The lowest mount bolt may require a universal joint socket driver and a long extender, but it is removable. Maneuver the heater core out of the truck and replace it with a new unit.

9. Installation is the reversal of removal, starting with the core itself. Position it through the dashboard gap, putting it's nipples through the firewall. Secure the mount bolts. Reassemble the dashboard, starting with the large mount bolts between the windshield. Reconnect the hoses and tighten the hose clamps in a clockwise direction. Splash a small amount of water on the hoses and area to remove any coolant smell, and allow it to dry. Reconnect the battery and run the Blazer with the heater on its highest setting, adding coolant to the system as required.

Tips & Warnings

• Use the proper type of coolant (some Blazer models vary in this year due to changeovers), either Dexcool (red) or universal (green/gold).

• Dispose of the coolant at a recycle center or auto parts store. Do not leave it out for animals--they find the coolant's smell appealing, but it will kill them if they drink it.

References

• All Experts: Chevy Blazer 2000 Heater Core Replacement