Where Is the Heater Core in a '95 Blazer?

The 1995 Chevrolet Blazer shares a platform with the GMC Jimmy, Chevrolet S-10 and GMC Sonoma pickups. It was equipped with either a 2.2-liter in-line-four cylinder or a 4.3-liter V-6 engine. The heater core in the Blazer works in a manner similar to the engine's radiator. When the heater is turned on, engine coolant flows through the heater core. Air is circulated through the core, where it is warmed and distributed through the various vents. The heater core is behind the dash on the passenger side of the vehicle. Accessing the heater core is a complex operation but can be accomplished by an experienced DIY mechanic.

Things You'll Need

• Wrench set
• Drain pan
• Masking tape and marker
• Phillips screwdriver
• Ratchet and socket set
• Torx bit set
• Flat-head screwdriver
• Inch-pound torque wrench

Instructions

Removal

1. Park the Blazer on a level surface and set the parking brake.

2. Allow the engine to cool. Disconnect the negative battery cable. Disengage the lockout function if the Blazer has a Delco Loc II stereo system. Slide a drain pan under the passenger side of the radiator. Loosen the drain plug and catch the coolant in the drain pan. Replace the drain plug. If the coolant is still clean, you can reuse it.

3. Loosen the heater hoses at the firewall with a flat-head screwdriver. Wrap a piece of masking tape around each hose and label it with a marker so you can put them back in the same position. Remove the hoses.

4. Move to the passenger compartment. Remove the left and right lower dash panels, which are held on with two screws and two clips. Remove the screws with a Phillips screwdriver. Use the Phillips screwdriver to remove the two screws from the instrument panel bezel. The screws are just above the instrument panel. Remove the bezel.

5. Remove the four screws that hold the instrument panel to the dash with a ratchet and socket. They are screws but have hex heads. Disconnect the electrical connectors and remove the panel. Remove the four screws that hold the radio in the dash with the ratchet and socket. Disconnect the antenna lead and wiring harness and remove the radio.

6. Look at each lower corner of the dash. You'll see a silver bracket at each corner. Remove the bolt running through it with a ratchet and socket. Remove the two Torx screws just above it with a ratchet and Torx bit. The brackets will allow you to tilt the dash away from the windshield, but not yet.

7. Remove the four nuts that attach the steering column to the firewall and dash with a ratchet and socket. Lower the steering column onto the seat. Move to the first vent on the passenger side of the dash. Look just below and to the left of the vent. You will see a bolt attached to a thin wire bracket. Remove the bolt with a ratchet and socket.

8. Move to the top of the dash and pry up the speaker and vent covers with a small flat-head screwdriver. Remove the screws -- also hex head -- with a ratchet and socket. Disconnect and remove the speakers. The dash will now pivot toward the rear of the Blazer.

9. At the right rear of the dash, disconnect the electrical connector. Lift the dash off its brackets and remove it.

10. Remove the bolts from the wire brace at the heater core cover and cowl with a ratchet and socket. It is held on with two bolts, one on the cover and one on the cowl. Remove the brace. Remove the six bolts from the heater core cover with a ratchet and socket. Remove the cover. You will see the heater core. It looks like a small radiator.

11. Remove the bolt from each corner of the heater core with a ratchet and socket. Where the metal heater core lines enter the firewall, there is a clamp; remove the screw with a Phillips screwdriver. Pull the core straight back and remove it

Installation

1. Slide the new core into place. Install the four bolts and clamp and screw. Install the cover and bolts with the socket and ratchet. Install the wire clamp and bolts.

2. Mount the dash on its brackets. Reconnect the electrical connector. Pivot the dash back into place and install the speakers and the screws along the top. Use a torque wrench to torque the screws to 17 inch-pounds, not foot-pounds. You will need a small inch-pound torque wrench for this. Install the vent and speaker grilles. Install the bracket bolts and Torx screws.

3. Install the radio and plug in the antenna and harness. Install the instrument panel and plug in the electrical connectors. Torque the instrument panel screws to 66 inch-pounds. Lift up the steering column and attach it to the firewall and dash with the four nuts. Install the bezel and its two screws. Install the lower dash panels.

4. Connect the heater hoses in the engine compartment. Fill the radiator with coolant. Reconnect the negative battery cable. Start the engine and check for leaks.

Tips & Warnings

• If you do not reuse your coolant, dispose of it properly. It is toxic.

References

• Haynes Chevrolet S-10 and GMC Sonoma Pick-ups 1994 through 1996 Blazer 1995 and 1996; Robert Maddox and John H. Haynes
• Auto Zone: Chevrolet Truck S10 Blazer 2WD 4.3L CPI 6cyl/Heater Core

Resources

• Read this Article in Spanish