Tools and Materials Needed:
- 10mm socket wrench
- 13mm socket wrench
- Phillips screwdriver
- Flat-head screwdriver
- Pliers
- New heater core (compatible with your vehicle)
- Coolant (proper type and amount for your Blazer)
- Funnel
- Rags
- Safety glasses
Step 1: Prepare the Vehicle
- Park the Blazer on a flat surface and ensure the engine is cool to the touch.
- Turn off the engine and disconnect the negative terminal of the battery.
Step 2: Locate the Heater Core
- Open the hood of the Blazer.
- Remove the plastic cover under the dashboard to access the heater core. This cover is typically held in place by clips or screws.
Step 3: Disconnect the Heater Hoses
- Locate the heater hoses connected to the heater core. These are usually two hoses, one for the inlet and one for the outlet.
- Use pliers to loosen the hose clamps and disconnect the hoses from the heater core. Make sure to place a rag beneath the hoses to catch any leaking coolant.
Step 4: Remove the Old Heater Core
- Use a 10mm socket wrench to remove the bolts that hold the heater core in place. There may be two or more bolts, depending on your specific Blazer model.
- Remove the old heater core from the housing. Be careful not to spill any remaining coolant.
Step 5: Clean the Housing
- Use a vacuum cleaner or a brush to clean the heater core housing. Remove any debris or dirt that may have accumulated.
Step 6: Install the New Heater Core
- Position the new heater core inside the housing.
- Secure the new heater core in place using the bolts you removed earlier. Tighten the bolts securely.
Step 7: Reconnect the Heater Hoses
- Reconnect the heater hoses to the heater core. Make sure the inlet hose is connected to the correct inlet port, and the outlet hose is connected to the correct outlet port.
- Tighten the hose clamps securely.
Step 8: Refill the Coolant
- Open the radiator cap or coolant reservoir (depending on your Blazer model) and add coolant until it reaches the recommended level indicated in your vehicle's owner's manual.
Step 9: Test the Heater
- Start the vehicle and let it warm up.
- Turn on the heater and ensure hot air is coming through the vents.
Step 10: Reattach the Cover
- Reattach the plastic cover that you removed in Step 2. Make sure it is securely in place.
Step 11: Restore Battery Connection
- Reconnect the negative terminal of the battery.
Step 12: Test Drive the Vehicle
- Take your Blazer for a test drive to ensure the heater is working properly.
Remember, this guide provides general steps, and specific details may vary depending on your vehicle's exact model and trim level. If you're unsure about any of the steps or encounter difficulties during the process, it's best to consult a trusted mechanic or refer to your vehicle's service manual for specific instructions.
