Tools and Materials Needed:
- Replacement heater core
- Drain pan
- Pliers
- Wrench set
- Socket wrench
- Flat head screwdriver
- Phillips head screwdriver
- Coolant (Dexcool or equivalent)
- Distilled water
Step-by-Step Instructions:
1. Safety Precautions:
- Allow the engine to cool down completely.
- Disconnect the negative terminal of the battery to avoid any electrical accidents.
2. Accessing the Heater Core:
- Open the hood and remove the air cleaner housing and any other obstructions that may block access to the heater core.
3. Draining the Coolant:
- Place a drain pan underneath the radiator.
- Open the radiator drain plug or petcock to drain most of the coolant into the drain pan.
- Close the drain plug once the coolant stops flowing.
4. Removing the Heater Core Cover:
- Locate the heater core cover inside the vehicle, typically under the dashboard on the passenger side.
- Use the screwdriver and wrench to remove any screws, clips, or bolts holding the cover in place.
- Be careful not to damage the dashboard or surrounding trim pieces.
5. Removing the Heater Hoses:
- Use a wrench to loosen and remove the heater hoses from the heater core connections. Be prepared for some coolant to spill.
- Plug or clamp the hose ends to prevent coolant loss.
6. Removing the Heater Core:
- Locate the bolts or nuts that hold the heater core in place, usually inside the engine compartment.
- Use the socket wrench to remove these bolts or nuts.
- Slide the old heater core out of its housing.
7. Installing the New Heater Core:
- Slide the new heater core into its housing. Make sure it sits securely in place.
- Install the bolts or nuts that you removed earlier, ensuring that the heater core is secured.
8. Reattaching the Heater Hoses:
- Reattach the heater hoses to their respective connections on the heater core. Tighten the hose clamps to secure them in place.
9. Refilling the Coolant System:
- Remove the radiator cap or fill plug.
- Mix the correct ratio of coolant and distilled water according to the vehicle's specifications.
- Slowly pour the coolant mixture into the radiator or coolant reservoir.
- Reinstall the radiator cap or fill plug.
10. Leak Check:
- Start the engine and let it run for a few minutes.
- Check for any coolant leaks around the heater core connections and hoses. Tighten any loose connections if necessary.
11. Reinstall Components:
- Reinstall the heater core cover, air cleaner housing, and any other components you removed during the process. Reconnect the negative battery terminal.
12. Test the Heater System:
- Turn on the heater controls inside the vehicle. Set the temperature to "high" and the fan speed to "low."
- Feel the air coming from the vents. It should be warm.
- If the heater blows cold air, there may be air trapped in the system. To remove the air, turn off the engine, squeeze the heater hoses several times, and then restart the engine. Repeat the process until you get warm air from the vents.
Remember that working with coolant can be messy, so it's a good idea to wear old clothes and gloves to protect yourself. If you encounter any difficulties, it's best to seek assistance from a qualified mechanic or refer to the vehicle's service manual for specific instructions related to your GMC Jimmy model.
